MimeKit

• Added a Received header parser.
• Marked HtmlToHtml.FilterHtml as obsolete to warn developers that this feature is not enough to protect against Cross-Size Scripting (XSS) vulnerabilities.
• Fixed logic for calculating maxOffset for Base64Encoder's hwaccel routines. (issue #1239)
• Capped the maxLineLength at 76 for Base64Encoder (which is what it used to be capped at until v4.14).
• Changed the default TnefPart mime-type to application/ms-tnef to match O365 Exchange behavior.
• Code quality improvements.

• Simplified logic for illegal ctrl characters within quoted-string local-part tokens in addr-specs.
• Fixed IndexOutOfRangeException in ParseUtils.TryParseMsgId(). (issue #1227)
• Improved ParseException message for invalid ctrl chars in quoted-strings.
• Improved recovery logic for InternetAddressList.TryParse().
• Fixed leak in X509Certificate2Extensions.GetPrivateKeyAsAsymmetricKeyParameter(). (issue #1230)
• Fixed potential integer overflow in TnefPropertyReader. (issue #1231)
• Added support for converting ECDsa PrivateKeys between Windows and BouncyCastle.
• Partial Encryption and Certificate Validation Failures for S/MIME. (issue #1224)
• Fixed MimeParser/MimeReader.ScanContent to not init local until needed. (issue #1234)
• Improved Received header folding logic.

• [SECURITY] Use stricter parsing logic for quoted-strings in addr-specs to prevent SMTP command injection attacks when those quoted-strings include CRLF sequences.

• Fixed inexact read in TnefPropertyReader.GetEmbeddedMessageReader().
• Fixed IndexOutOfRangeException in DateTImeUtils.TryParse() when missing timezone after AM/PM. (issue #1204)
• Added nullable attributes to the API. (issue #1067)
• AuthenticationResults parsing now supports Gmail style headers. (issue #1208)
• Changed the Base64Decoder to no longer default to enabling hardware acceleration due to bugs in System.Buffers.Text.Base64.DecodeFromUtf8 (will likely be fixed in .NET 11). (issue #1215)
• Improved SqlCertificateDatabase abstraction to make it easier to subclass when the SQL syntax does not match SQLite. (issue #1218)
• Bumped System.Buffers to 4.6.1 and System.Memory to 4.6.3.
• Bumped BouncyCastle.Cryptography to 2.6.2.
• Added support for .NET 10.

• Updated BouncyCastle.Cryptography dependency to v2.6.1.
• Added BodyBuilder.BodyEncoding property to allow setting body text encoding.
• Fixed a number of TnefPropertyTags that didn't have proper Type info.
• Added TnefPropertyTag.PuidA and TnefPropertyTag.PuidW and Obsoleted TnefPropertyTag.Puid.
• Fixed TnefPropertyTag.ToUnicode() to only affect String8 tags.
• Optimized the Base64Encoder to use hardware acceleration when available.
• Optimized the Base64Decoder to use hardware acceleration when available.
• Fixed parsing of short StatusGroups in MessageDeliveryStatus (issue #1181)
• Fixed MimeParser and ExperimentalMimeParser to consistently adhere to ParserOptions.MaxMimeDepth.
• Fixed MimeParser and ExperimentalMimeParser to properly (re)initialize their MboxMarker and MboxMarkerOffset properties before parsing each message in an mbox stream. When parsing fails, these properties will now have values of null and -1, respectively.
• Fixed MultipartSigned.Create() to avoid corrupting binary content of the entity (or child entities) being signed (important for AS2 messages). (issue #1184)
  • Note: It is important for developers to properly set the ContentTransferEncoding of these parts to ContentEncoding.Binary to avoid corruption.
• Fixed MimeParser, ExperimentalMimeParser and MimeReader to handle header lines that exceed the internal input buffer length. (issue #1189)
• Obsoleted DkimSignerBase, DkimSigner, and ArcSigner .ctors that did not take a parameter that could be used to initialize the PrivateKey property.
• Obsoleted DkimSignerBase.PrivateKey property setter.

• Fixed a memory leak in MimeAnonymizer and MimeUtils.Unquote() which gets used by the address parser. (issue #1161)
• Optimized MimeReader and MimeParser to use Span<T>.IndexOf() on .NET Core which can improve performance by 20-30% when parsing MemoryStreams or 5-10% when parsing FileStreams.
• Optimized the MboxFromFilter and ArmoredFromFilter by using Span<T>.IndexOf().
• Fixed S/MIME logic to allow certificates without the KeyEncipherment key usage for encryption. (issue #1165)
• Added MimeAnonymizer.PreserveHeaders as a way of preventing anonymization for specific headers.
• Added message/deliver-status and message/disposition-notification support to MimeAnonymizer.
• Slightly optimized the Unix2DosFilter.

• Removed CTRL characters from the list of allowed domain characters.
• Fixed a bug in the address list parser in Strict mode that allowed 2 addresses to be separated by whitespace instead of requiring a comma.
• Added a new MimeAnonymizer class that can be used to anonymize MimeMessages by x-ing out non-syntactically relevant information.
• Fixed TryParse methods to not throw ArgumentExceptions. (issue #1158)
• Fixed a bug in MimeReader that used the buffer offset instead of the stream offset to check if the stream position was beyond the byte offset specified by a Content-Length header when parsing UNIX mbox files.
• Fixed a long-standing bug in MimeParser (which also existed in MimeReader) where it would encounter a buffering bug when parsing some Mbox files (typically multi-gigabyte). (issue #991)
• Fixed AttachmentCollection.Add/AddAsync methods to dispose the MimePart it is creating if loading content fails from the stream fails.
• Added leaveOpen parameters for HtmlWriter .ctors. (issue #1159)
• Fixed parsing when ParserOptions.AllowUnquotedCommasInAddresses = false. This used to incorrectly allow unquoted commas in address Display Names if the comma followed at least 2 words.

• Fixed logic for validating HTML Tag and Attribute names. (issue #1136)
• Minor performance improvements to MimeParser, ExperimentalMimeParser, and MimeReader.
• Obsoleted MimeReader.OnMultipartBoundary() and OnMultipartEndBoundary(), replacing them with OnMultipartBoundaryBegin/Read/End() and OnMultipartEndBoundaryBegin/Read/End(). This now allows ExperimentalMimeParser to track trailing whitespace on boundary lines, resulting in improved re-serialization of parsed messages.
• Fixed serialization of message/rfc822 parts without a message.
• Fixed serialization of messages that did not have a blank line between the headers and body (only when parsed using the ExperimentalMimeParser).
• When using DbTransactions, set the transaction on the DbCommands. (issue #1142)
• Improved Date header parser for JST and KST timezones.
• Improved Date header parser to handle AM/PM and leap seconds.
• Improved address parser to handle unbalanced ')' (rfc7103)
• Bumped System.Security.Cryptography.Pkcs dependency to 9.0.2.
• Bumped System.Text.Encoding.CodePages dependency to 9.0.2.

• Fixed logic for converting BouncyCastle DSA keys to System.Security equivalents.
• Fixed BouncyCastleSecureMimeContext to respect the CheckCertificateRevocation property when encrypting to recipeints and when verifying signatures.
• Marked IX509CertificateDatabase.Update(X509CrlRecord) as obsolete.
• Fixed TemporarySecureMimeContext.Import(X509Crl) to not import duplicates.
• Added new MimeMessage .ctor that takes IEnumerable<Header>.
• Fixed MimeReader to better handle garbage at the start of an mbox.
• Fixed MimeReader/ExperimentalMimeParser to handle really long mbox markers by introducing 2 new methods: OnMboxMarkerBegin() and OnMboxMarkerEnd().
• Improved MimeReader header parsing (mostly just state tracking improvements) which allows it to throw the appropriate exception if EOS is reached before parsing any headers.
• Make sure to flush any remaining text in the FlowedToText and FlowedToHtml converters (issue #1130)
• Fixed Header folding/encoding logic for Original-Message-ID by making it follow the same rules as Message-ID/Content-ID/etc. (issue #1133)

• Started adding some DynamicallyAccessedMembers attributes for AOT compatibility.
• Refactored some code for AOT Compatibility (MimeKitLite is now 100% AOT Compatible but MimeKit still has issues related to SQLite database loading for the S/MIME certificate database). (MailKit issue #10844)
• Fixed TextPreviewer to use an encoding with an empty string fallback to prevent '?' characters from being appended to the generated preview string if the byte sequence was truncated.
• Improved performance of InternetAddressList.Parse()/TryParse().
• Improved InternetAddressList parser performance for malformed addresses that only contain display-name strings separated by commas. (issue #1106)
• Exposed BouncyCastleCertificateExtensions.IsSelfSigned(), GetKeyUsageFlags() and IsDelta() as new public APIs.
• Exposed X509KeyUsageBits enum as public.
• Added support for domain-bound S/MIME certificates. (issue #1113)
• Dropped support for net6.0 in the nuget packages (Microsoft support ended Nov 12, 2024).
• Removed explicit dependency on System.Runtime.CompilerServices.Unsafe.
• Bumped System.Security.Cryptography.Pkcs dependency to v8.0.1.
• Bumped BouncyCastle.Cryptography dependency to v2.5.0.
• Bumped System.Buffers dependency to v4.6.0.
• Bumped System.Memory dependency to v4.6.0.

• Added TypeConverters for InternetAddress and InternetAddressList.

• Bumped System.Formats.Asn1 to v8.0.1 to fix a denial of service security issue.

• Bumped BouncyCastle.Cryptography from 2.3.1 to 2.4.0
• Don't override the parameter encoding with UTF-8 if format.International is true. (issue #1041)
• Fixed BouncyCastle S/MIME backend to properly encrypt/decrypt for SubjectKeyIdentifier. (BouncyCastle issue #532)
• Added support for addresses like "webmaster@custom-host.com@mail-host.com". (issue #1043)
• Improved Content-Type and Content-Disposition parameter serialization in a few cases.
• Added tests for HeaderList.set_Item[int index] and fixed a bug that was exposed.
• Fixed ContentDisposition.Size parsing to use InvariantCulture.
• Fixed parser logic for determining if a message/rfc822 part is encoded. (issue #1049)

• Fixed hex format specifier for PGP keyserver lookup. (issue #1028)
• Bumped the BouncyCastle.Cryptography dependency to v2.3.1 to fix some security issues.
• Fixed a bug in conversion logic between BouncyCastle DSA key parameters and System.Security.Cryptography's DSA implementation.

• Fixed MailboxAddress to not use punycode to encode or decode the local-part of an addr-spec. (issue #1012)
• Removed explicit refs to CompilerServices.Unsafe and Encoding.CodePages from net6.0/8.0. (issue #1013)

• Added net8.0 target.
• Improved folding logic for Disposition-Notification-Options header values. (issue #979)
• Added interfaces for MimeMessage, MimeEntity, MimePart, Multipart, etc. (issue #980)
• Fixed the FormatOptions.NewLineFormat setter logic.
• Modified AttachmentCollection.Add() for message/rfc822 attachments to better handle MimeParser exceptions. (issue #1001)
• Bump BouncyCastle dependency to v2.3.0.
• Added support for ECC S/MIME certificates. (issue #998)
• Improved Unix2Dos and Dos2Unix filters by fixing some corner cases exposed by new unit tests.
• Fixed MaxMimeDepth logic to still use MimePart subclasses when reached. (issue #1006)

• Added work-around for broken Message-ID header values of the form <id@@domain>. (issue #962)
• Added virtual Multipart.TryGetValue(TextFormat, out TextPart) method that recursively iterates over child parts to find the TextPart with the desired format.
• Fixed MimeMessage.TextBody/HtmlBody to locate the text body in a multipart/mixed that is inside of a multipart/alternative. This resolves an issue locating the text body within some broken iOS Apple Mail messages. (issue #963)

• Follow the spec more closely for allowable header field characters. (issue #936)
• Avoid throwing NRE when an RC2 algorithm was used for S/MIME w/o parameters. (issue #941)
• Added a few more (undocumented) TnefPropertyIds.
• Optimized AttachmentCollection.Add(byte[], ...) by not copying the data to a new stream.
• Improved performance of HtmlTokenizer.
• Added new HtmlTokenizer constructors that take a Stream instead of a TextReader. This allows for a slight performance improvement over using a TextReader as well.
• Lazy-allocate Base64/QuotedPrintable decoders when decoding rfc2047-encoded headers. This is a very small reduction in GC pressure.
• Reduced memory allocations in Rfc2047.DecodePhrase() and DecodeText().
• Avoid allocating empty List<string>s in DomainList.ctor(), lazily allocate the list only when a domain is added. Another minor reduction in GC pressure.
• Updated the Date parser to allocate an internal list of tokens with a optimal initial capacity to avoid the need for reallocating.

• Readded the System.Net.Mail-to-MimeKit conversion APIs for the netstandard2.x frameworks. (issue #913)
• Fixed the MimeEntity.LoadAsync() overloads that take a ContentType parameter to to properly wait to dispose of the stream until after the entity has been parsed. (issue #916)
• Optimized conversion between HeaderId and string.
• Added a new IMimeParser interface that both MimeParser and ExperimentalMimePraser implement.
• Added "unicode" to the list of charset aliases for UTF-8. (issue #923)
• Added support for the Edwards Curve DSA PGP public key algorithm. (issue #932)
• Bumped System.Security.Cryptography.Pkcs dependency to 7.0.2.
• Bumped BouncyCastle dependency to 2.2.1.

• Ported to BouncyCastle v2.1.1. (issue #865)
• Fixed System.Net.Mail.MailMessage -> MimeMessage converter to reset MailMessage attachment/alternateview streams back to 0 after copying them. (issue #907)
• Added support for the signature expiration field in DKIM signatures which can be specified using the new DkimSigner.SignatureExpiresAfter property.
• Added equality operators for TnefNameId and TnefPropertyTag.
• Fixed MimeMessage's MessageId, ResentMessageId and InReplyTo property setters to be more lax. (issue #912)
• MimeKit and MimeKitLite nuget packages now include MimeKit.dll.config that contain assembly redirects which may resolve some issues some developers were having with loading assemblies such as System.Runtime.CompilerServices.Unsafe.dll.

• Improved the UrlScanner to allow numeric key/value pairs (seems to match behavior in other url detection algorithms).
• Fixed a mis-use of ArrayPool in the OpenPgpContext.Encrypt/EncryptAsync that could cause memory corruption.
• Use BitConverter to decode floats/doubles from the input buffer instead of custom code.
• Bumped the System.Security.Cryptography.Pkcs dependency to v6.0.2.

• Added the .msg <-> application/vnd.ms-outlook mime-type mapping. (issue #880)
• Improved encoding/formatting of List-Archive, List-Help, List-Post, List-Subscribe and List-Unsubscribe headers. (issue #885)
• Reduced memory allocations when encoding the mailbox/group names.
• Added more Rfc2047.EncodePhrase()/EncodeText() overloads that take startIndex and count arguments.
• Fixed parsing of Message-Id's containing a quoted string dot-atom (among regular dot-atoms). (issue #889)
• Fixed a bug in the parsing of HTML <script> content that sometimes caused a character to be duplicated.
• Use MailMessage.HeadersEncoding when coverting a MailMessage to a MimeMessage.
• Improved the UrlScanner to accept urls like https://example.com?query (issue #897)

• Fixed potential NRE's in the GnuPG config parser
• Modified AsBouncyCastleCertificate() extension method to throw on fail
• Added Clone() methods to ContentType, ContentDisposition and Parameter.

• Fixed a variety of memory leaks revealed by (issue #852)
• Fixed the message/delivery-status parser to handle extra blank lines between status groups. (issue #855)
• Updated packages to explicitly depend on System.Runtime.CompilerServices.Unsafe v6.0.0.
• Updated net6.0 dependencies to explicitly include System.Text.Encoding.CodePages v6.0.0.

• Fixed MessageDeliveryStatus.ParseStatusGroups() to catch FormatException instead of ParseException. (issue #837)
• Fixed DefaultSecureMimeContext to use the correct AppData path on Windows.
• Fixed MimeMessage .ctor(params object[] args) to respect a Date header argument. (issue #840)
• Updated MIME-Type to file extension mappings to add a few missing types/extensions. (issue #844)
• Fixed address parser to no longer throw ArgumentOutOfRangeException when parsing some mailbox names. (issue #846 and #847)
• Map codepage 932 to shift_jis instead of iso-2022-jp. (issue #848)

• Improved logic for reformatting headers when MimeMessage.WriteTo() is called with FormatOptions.International set to true.
• Fixed logic for quoting and/or encoding the MailboxAddress.Name in cases where the Name string contains quotes or parenthesis (especially when unicode characters are within the quotes or parenthesis).
• Improved logic in the address parser when it comes to unquoting mailbox names (i.o.w. unquote before decoding rather than after).
• Modified the Message-ID/Content-ID parser to be more lenient. (issue #835)

• Introduced a new IPunycode interface and Punycode class allowing developers to override the default implementation that uses .NET's IdnMapping class. (issue #801)
• Added HtmlAttributeCollection Contains, IndexOf and TryGetValue methods.
• Dropped .NET5.0 support.
• Changed HtmlToHtml converter to avoid decoding character references. (issue #808)
• Fixed BoundStream to only seek in the base stream if seeking is supported.
• Added a new TextPart.TryDetectEncoding() API. (issue #804)
• Added support for message/feedback-report via a new MessageFeedbackReport class.
• Fixed a potential memory leak.
• When unquoting parameter values, don't convert tabs to spaces. (issue #809)
• Don't call Encoding.RegisterProvider() anymore. Rely on developers doing this themselves in their application startup logic.
• Remove System.Text.Encoding.CodePages dependency for net4x.
• Expose the LineNumber property on MimeMessageBeginEventArgs and MimeEntityBeginEventArgs. (issue #819)

• Added Import() methods for X509Certificate2 for all S/MIME contexts. (issue #784)
• Handle S/MIME sha# as well as sha-# micalg names for improved interop. (issue #790)
• Fixed the MemoryBlockStream.Read() method to handle cases where the length of the stream is longer than int.MaxValue.
• Fixed TnefPart.ConvertToMessage() to promote lone multipart/mixed subparts to become the message body much like it used to work pre-v3.2.0. (issue #789)
• Reduced memory usage when using SecureMimeContext.Compress() and CompressAsync().
• Dropped support for net452 and net461 now that their life cycles have ended and are no longer supported by Microsoft. (issue #768)
• Added support for net462.

Special thanks to Fedir Klymenko for his improvements to MemoryBlockStream and SecureMimeContext.Compress!

• Rewrote QuotedPrintableEncoder to more strictly fold at the specified line length. (issue #781)
• Change the default maxLineLength for quoted-printable/base64 encoders to 76 to match the recommendation in the specification (was previously 72).
• Use cached Task instances (e.g. Task.CompletedTask) when possible to improve performance.
• Make use of ReadOnlySpan<T> instead of String.Substring() wherever possible to improve performance.
• Reduced string allocations in other ways.
• Provide MailboxAddress accessors for LocalPart and Domain. (issue #766)
• Replaced support for .NET Framework v4.6 with 4.6.1 and added a System.Text.Encoding.CodePages dependency to solve various cases where MimeKit would fail to initialize properly on ASP.NET systems using net461 when system character encodings were not available.
• Fixed MessagePartial to use invariant culture when setting number/total param values.
• Make sure all int.TryParse() calls use the correct NumberStyles.
• Make use of a ValueStringBuilder to construct strings without needing to allocate a StringBuilder.
• Fixed InternetAddressList.TryParse() to fail on invalid input. (issue #762)
• Added dispose handling to MimeMessage.CreateFromMailMessage().
• Improved MIME structure returned by TnefPart.ConvertToMessage().
• Rewrote header folding logic to avoid string allocations.
• Implemented IEquatable<T> on TnefNameId.
• If iso-8859-1 isn't available, fall back to ASCII instead of Windows-1252. (issue #751)

Special Thanks to Jason Nelson for taking the lead on many of the listed (and unlisted) performance improvements and helping me make MimeKit even more awesome!

• When initializing character encodings for netstandard and net50/net60, wrap the Reflection logic to invoke System.Text.Encoding.RegisterProvider() in a try/catch to prevents exceptions when using the netstandard version of MimeKit in a .NET Framework app. (issue #751)
• Added a work-around for Office365 message/delivery-status parts where all status groups after the first are base64 encoded. This seems to be a bug in Office365 where it treats the first status group as MIME entity and the following status groups as the content. (issue #250)
• Fixed the MimeMessage .ctor that takes object parameters to first check that a Message-Id header was not supplied before generating one for the message. (issue #747)
• Fixed the BestEncodingFilter logic such that if any line in binary content is > 998 and it contains nul bytes, it should recommend base64 (not quoted-printable).

• Always use a lowercase domain name in the Message-Id to work around bugs in eM Client. (issue #734)
• Improved handling of parsing Content-Types like "multipart/multipart/mixed; boundary=...". (issue #737)
• Added a maxLineLength argument to the QuotedPrintableEncoder .ctor.
• Added maxLineLength arguments to EncoderFilter.Create() methods.
• Fixed MimePart.Prepare() to remember the maxLineLength argument value for later use in the WriteTo() implementation. This maxLineLength value can then be passed to the Base64 or QuotedPrintable encoder so that it can properly limit lines to that length (up to a max of 76 characters as per the specs). (issue #743)
• Added net6.0 to the list of TargetFrameworks.

• Removed APIs marked as [Obsolete] in 2.x.
• Refactored X509CertificateDatabase protected methods to include a DbConnection parameter.
• Removed OpenPgpContextBase by folding the logic into OpenPgpContext.
• Added Async APIs for OpenPGP and S/MIME.
• Lazy-load headers on MimeMessage and MimeEntity (and subclasses) to improve performance.
• Added a new MimeReader class that acts as a lower-level MimeParser alternative, allowing developers to parse MIME content without having to instantiate a MIME tree of objects or wait until the parser has completed (and returned a MimeMessage or MimeEntity object) before processing MIME data. This is conceptually similar to a SAX XML parser approach.
• Added a new ExperimentalMimeParser that duplicates MimeParser functionality, but is built on top of MimeReader. This implementation will eventually replace MimeParser once I get some feedback on it. Should be ~5% faster than MimeParser.
• Improved MimeParser performance slightly based on some of the experimentation done to make the ExperimentalMimeParser fast.
• Added CancellationToken arguments for some AttachmentCollection.Add() overloads.
• Use 'net5.0' as the .NET 5.0 target framework moniker instead of 'net50'. (issue #720)
• Drop support for .NET 4.5 and replace it with .NET 4.5.2
• Bumped Portable.BouncyCastle to 1.9.0
• Added new MimeMessage.GetRecipients() method.
• Make it possible to bypass MimeEntity preparation for signing by adding a PrepareBeforeSigning property to CryptographyContext. (issue #721)
• MimeMessage and MimeEntity now implement IDisposable. (issue #732)

• Improved MimeParser to be a little more efficient based on work being done for the upcoming v3.0 release.
• Fixed a bug in the MimeParser exposed by added unit tests regarding Content-Length handling.
• Improved address parser error messages.
• Fixed MailboxAddress.Address to be forgiving if there is trailing whitespace after the addr-spec token when setting MailboxAddress.Address. (issue #705)
• Fixed MimeMessage and MimeEntity.ToString() to not write a newline before the message/entity (regression introduced in 2.14.0).

• Use DebugType=full for .NET Framework v4.x. (MailKit issue #1239)
• Fixed bug in MultipartSigned.VerifyAsync() that would dispose of the crypto context before the async task was complete, resulting in an OperationCanceledException.
• Default to using the Environment.SpecialFolder.UserProfile directory instead of Personal when GNUPGHOME isn't defined in the environment. The Personal directory maps to the MyDocuments directory, so this wasn't correct. The .gnupg directory should be in the user's HOME directory.
• Added ContentType.ToString(bool encode) and ContentDisposition.ToString(bool encode) convenience methods.
• Changed the public Header.Parse/TryParse APIs to canonicalize header values to end with a newline even if the input string does not. (issue #695)

• Allow ..'s and trailing .'s in the local-part of an addr-spec by introducing a new RfcComplianceMode.Looser enum value that can be set on the ParserOptions.AddressParserComplianceMode property. (issue #682)
• Use Reflection to call Encoding.RegisterProvider() so that referencing the netstandard MimeKit assemblies from .NET 4.8 won't crash. (issue #683)
• Don't write the X-MimeKit warning header in ToString() anymore. This is a lost cause.
• Updated the OpenPgpContext to default to keys.openpgp.org since keys.gnupg.net does not resolve via DNS anymore.

• Added a way to force MimeKit to always quote parameter values. (issue #674)
• Fixed PGP/MIME signatures to use the proper BEGIN/END PGP SIGNATURE markers instead of BEGIN/END PGP MESSAGE markers by avoiding compressing the PGP signature packet. (issue #681)

• Fixed S/MIME support using WindowsSecureMimeContext with MimeKit's CmsSigner classes which was causing a PlatformNotSupportedException. (issue #664)
• When extracting HTML from TNEF, try to use the charset delcared in the HTML's meta tags. (issue #667)
• Added AttachmentCollection.AddAsync() methods. (issue #670)
• Enable SqliteCertificateDatabase initialization logic for .NET v5.0. (issue #673)

• Fixed DSA key conversion logic to work more reliably.
• Catch exceptions from IPGlobalProperties.GetIPGlobalProperties() and fall back to localhost. (issue #630)
• Fixed base64 encoder to only flush with a newline if it is midline. (issue #646)
• Added .NET 5 build targets and include in the nuget packages.
• Added a new GnuPGContext .ctor that allows specifying a custom path.
• Bumped Portable.BouncyCastle dependency to 1.8.10.
• Improved HtmlWriter ArgumentException messages.

• Treat message/disposition-notification and message/delivery-status the same as text/* when preparing for signing. (issue #626)
• Always set Content-Disposition: inline for BodyBuilder.LinkedResources. This fixes a regression introduced in 2.10.0. (issue #627)
• Fixed NuGet package references to System.Data.DataSetExtensions for netstandard2.1 and net4x.

• Added SQL Server support. (issue #619)
• Fixed a leak in SqlCertificateDatabase when creating the certificates database.
• Bumped BouncyCastle dependency to v1.8.8. (issue #610)
• Exposed some ArcVerifier and DkimVerifier internal methods. (issue #601)
• Improved MimeParser performance.
• Fixed potential leaks in MimeParser when loading MimePart content in exception cases.
• Made use of ArrayPools for various buffers which may help performance. (issue #616)
• Fixed MimeUtils.GenerateMessageId() to encode international domain names.
• Fixed MimeUtils.GenerateMessageId() to cache the local hostname. (issue #612)
• Modified AttachmentCollection to use a custom implementation of Path.GetFileName() that allows illegal path characters.
• Only generate a ContentId for the MultipartRelated Root if it is not the first part.

• Include WindowsSecureMimeContext in the .NET Standard 2.x build. (issue #600)
• Fixed message.Prepare() to never choose the quoted-printable encoding for non-text based MimeParts. (issue #598)
• Added work-around for mailers that don't use a ';' between Content-Type and Content-Disposition parameters. (issue #595)
• Added improved error reporting for ArcVerifier. (issue #591)
• Added another work-around for parsing Authentication-Results headers. (issue #590)
• MimeMessage.ToString() now adds an X-MimeKit-Warning header to the beginning of the output string to make it clear to developers doing this that they are Doing it Wrong(tm).
• Added a TLS-Required HeaderId enum value.

• Refactored OpenPgpContext to separate out key storage implementation. (issue #576)
• Fixed the TextToFlowed converter. (issue #580)
• Protect against ABRs in AuthenticationResults.TryParse(). (issue #581)
• The net45 version of MimeKit now depends on Portable.BouncyCastle instead of official BouncyCastle.
• Added MimeParser events to report stream offsets for MimeMessages and MimeEntities. (issue #582)
• Fixed DkimPublicKeyLocatorBase to treat unspecified 'k' values in DKIM DNS records as "k=rsa". (issue #583)
• Fixed date format serializer to use CultureInfo.InvariantCulture.
• Fixed AuthenticationResults parser to allow '_' characters in method results. (issue #584)
• Improved RSACng and DSACng support.

• Improved logic for verifying signatures for MimeParts containing mixed line endings. (issue #569)
• Fixed MailboxAddress parser to decode IDN-encoded local-parts of email addresses. (MailKit issue #1026)
• Added new MailboxAddress.GetAddress(bool idnEncode) method.
• Improved subclassability of OpenPgpContext by making a number of methods virtual. (issue #571)
• Added support for RSACng and DSACng. (issue #567)
• Dropped Xamarin platforms since they are compatible with netstandard2.0.

• Fixed InternetAddressList.Insert() to allow inserting at the end of the list. (issue #559)
• Added ParserOptions.MaxMimeDepth to allow developers to set the max nesting depth allowed by the parser.
• Added logic to handle multipart children without any headers or content.
• Added a new Verify(bool verifySignatureOnly) method to IDigitalSignature for developers who just want to be able to verify the signature without worrying about the certificate chain.
• Fixed MimePart.WriteTo() to avoid canonicalizing line endings for MimeParts that do not define a Content-Transfer-Encoding. (issue #569)
• NuGet packages now include the portable pdb's.

• Fixed the MimeEntity.ContentId setter to use ParseUtils.TryParseMsgId() instead of MailboxAddress.TryParse() so that it is more lenient in what it accepts. (issue #542)
• Added an HtmlTokenizer.IgnoreTruncatedTags property which is useful when working with truncated HTML.
• Optimized the heck out of HtmlEntityDecoder.
• Added a TextPart.Format property for a quick way to determine the type of text it contains.
• Added text/plain and text/html preview/snippet generators (PlainTextPreviewer and HtmlTextPreviewer, respectively). This is part of a larger improvement to MailKit's text preview feature for IMAP. (MailKit issue #1001)
• Fixed SqlCertificateDatabase to accept null SubjectKeyIdentifiers.
• Changed Header.FormatRawValue() to be protected virtual and added Header.SetRawValue() to allow developers to override the default formatting behavior by either subclassing Header or by calling header.SetRawValue(). (issue #546)
• Switched MimeKit for Android and iOS over to using Portable.BouncyCastle.
• Added MimeTypes.Register() to allow developers to register their own mime-type mappings to file extensions.

• Updated net46, net47, and net48 builds to reference Portable.BouncyCastle instead of the standard BouncyCastle package, just like the netstandard builds. (issue #540)
• Fixed extraction of TNEF EmbeddedMessage attachment data to skip the leading GUID. (issue #538)
• Added a few more TNEF property tags.
• Fixed the HtmlEntityDecoder to require some named attributes to end with a ;.

• Fixed parsing of email addresses containing unicode or other types of 8-bit text. (issue #536)
• Added a MimeTypes.TryGetExtension() method to try and get a file name extension based on a mime-type. (issue #534)
• Updated mime-type mappings.

• Fixed message reserialization after prepending headers. (issue #524)
• Added a ContentType.CharsetEncoding property. (issue #526)
• Allow empty prop-spec token values in Authentication-Results headers. (issue #527)
• Added logic to quote Authentication-Results pvalue tokens if needed.
• Added support for converting RSACng keys into BouncyCastle keys for net4x versions that support it.
• Added support for RSAES-OAEP for the BouncyCastle backend. (issue #528)
• Updated and changed the API for RSASSA-PSS. CmsSigner now has a RsaSignaturePadding property which obsoletes the previous RsaSignaturePaddingScheme property.
• Added more columns to the default SQLite database CERTIFICATES table that allow more optimal SQL searches for certificates given various matching criteria.
• Fixed WindowsSecureMimeContext.Decrypt() to make sure it doesn't stop at the first failed recipient. (issue #530)
• Fixed splitting and reassembly of message/partial messages.
• Improved handling of Office365 Authentication-Results headers by adding a Office365AuthenticationServiceIdentifier property to the AuthenticationMethodResult class.
• Fixed mailbox address parser to be more lenient about "[" and "]" characters in the display-name. (issue #532)

• Don't use PublicSign on non-Windows NT machines when building. (issue #516)
• Improved BouncyCastleSecureMimeContext logic for building certificate chains so that certificate chains are included in the S/MIME signature. (issue #515)
• Improved SqlCertificateDatabase.Find() by using more IX509Selector properties.
• Relaxed the Authentication-Results header parser a bit to allow '/' in pvalue tokens. (issue #518)

• Added the text/csv mime-type to the MimeTypes mapping table for files with a .csv extension.
• Expanded the .NETStandard API to match the .NET 4.5 API, so .NETStandard is now complete.
• Dropped support for .NETPortable and WindowsPhone/Universal v8.1.
• Added a net48 assembly to the NuGet package.
• Improved HTML tokenizer performance.
• Fixed X509Crl.IsDelta for CRLs without extensions. (issue #513)
• Added support for message/global-delivery-status, message/global-disposition-notification, and message/global-headers to MimeParser. (issue #514)
• Fixed S/MIME signatures generated by a TemporarySecureMimeContext to include the certificate chain. (issue #515)

• Fixed reserialization of message/rfc822 parts to not add an extra new-line sequence to the end of the message. (issue #510)
• Fixed DefaultSecureMimeContext to build the cert chain outside of the private key query. (issue #508)
• Modified the Message-Id parser to gobble ctrl chars in the local-part.
• Fixed some buglets in the TextToFlowed converter involving space-stuffing lines.
• Fixed BodyBuilder logic for constructing a body with an HtmlBody set to string.Empty. (issue #506)
• Fixed potential memory leaks in WindowsSecureMimeContext and BouncyCastleSecureMimeContext in the Export() methods in cases where an exception is throw while adding certificates.
• Removed MimeKit.Cryptography.NpgsqlCertificateDatabase. It is unlikely anyone actually uses this.

• Updated CmsSigner's default DigestAlgorithm to Sha256 instead of Sha1 to match System.Security.Cryptography.Pkcs.CmsSigner's default.
• Updated WindowsSecureMimeContext to default to IssuerAndSerialNumber for System.Security.Cryptography.Pkcs.CmsSigner.
• Added support for the RSASSA-PSS signature padding algorithm when using the BouncyCastle backend.
• Improved robustness of TNEF processing of email address fields.
• Modified FilteredStream.Flush*() to not flush the source stream. (MailKit issue #904)
• Added net46 and net47 assemblies to the NuGet package.

• Fixed MultipartRelated to fall back to the multipart/related type parameter when locating the Root. (issue #489)
• Improved Authentication-Results parser to handle non-standard syntax. (issue #490)
• When FormatOptions.AllowMixedHeaderCharsets is disabled, always use the user-specified charset. Previously this could/would still use us-ascii and/or iso-8859-1 if the entire header could fit within one of those charsets. (issue #493)
• Fixed the line length calculations in the BestEncodingFilter. (issue #497)
• Fixed Multipart to properly ensure the epilogue ends w/ a new-line when FormatOptions.EnsureNewLine is true. (issue #499)
• Modified Multipart.WriteTo[Async] to not ensure that a Content-Type boundary parameter has been set. This code-path was only hit if the multipart was parsed by the parser and did not have a boundary parameter in the first place. In the interest of preserving byte-for-byte compatibility with the original input, this sanity check has been removed. (issue #499)

• Added support for ARC.
• Added AuthenticationResults class for parsing and constructing Authentication-Results and ARC-Authentication-Results headers.
• Added support for the Ed25519-SHA256 DKIM signature algorithm.
• Obsoleted MimeMessage DKIM API's in favor of the newer DKIM API's:
  • MimeMessage.Sign (DkimSigner, ...) has been replaced by DkimSigner.Sign (MimeMessage, ...).
  • MimeMessage.Verify (Header, ...) has been replaced by DkimVerifier.Verify (MimeMessage, Header, ...).
• Added DkimPublicKeyLocatorBase to help simplify implementing IDkimPublicKeyLocator.

• Updated the BouncyCastle assemblies to version 1.8.5 for iOS and Android.
• Fixed a possible NullReferenceException when decoding S/MIME digital signatures.
• Fixed the netstandard2.0 dependencies to no longer explicitly include System.Net.Http. (issue #482)
• Override Equals(object) and GetHashCode() for InternetAddress and InternetAddressList. (issue #481)
• Fixed TnefReader.Dispose() to avoid a potential NullReferenceException if double disposed.
• Fixed the Message-Id, Content-Id, References and In-Reply-To parsers to be more liberal in what they accept in terms of the msg-id token.
• Changed the Header encoding logic for the In-Reply-To header to not rfc2047 encode the value even if it is longer than the suggested line-length. (issue #479)
• Reduced netstandard dependencies. (issue #475)

• Added a setter for FormatOptions.MaxLineLength, allowing developers to override this value.
• Improved TNEF handling of Content-Disposition and Content-Id properties. (issue #470 and issue #471)
• Improved Content-Id parser to be more forgiving with improperly formatted IDs. (issue #472)
• Added support for the text/rfc822-headers MIME-type via the new TextRfc822Headers class. (issue #474)
• Added fallback logic for international email addresses that are not properly encoded in UTF-8. (issue #477)