v0.3.9 SMTP client port, debug logging and more

[wneessen]

This release is the biggest since the initial release of the library. While there wasn't really much change on the surface, there happend a lot under the hood.

net/smtp fork

go-mail heavily relies on the Go stdlib net/smtp package. Unfortunately this lib is in feature freeze mode, so that enhancing/extending the package is not possible. This restricted us - at least to a certain degree - as we can't add features that would be useful for go-mail. For that reason we ported/forked the whole package over and adjusted all parts of go-mail to use it instead.

The original license has been imported and the license headers have been adjusted to reflect the go-mail's MIT license and the original Go BSD-3-Clause license. Additionally, the license headers have been converted to SPDX style.

Debug logging

Since we now have full control over the SMTP client part of go-mail, this allowed us to implement ldebug logging for the SMTP communication. Via the Client.WithDebugLog client option the user can enable this feature. It will then make use of the new smtp/Client.SetDebugLog method. Once the flag is set to true, the SMTP client will start logging incoming and outgoing messages to os.Stderr.

We've also implemented a simple log.Logger interface, as well as a standard logger that satisfies this interface. This allows the user to provide a custom logger, as long as the interface is stasified. If no custom logger is provided, the Stdlog will be used (which makes use of the Go stdlib again). Accordingly, a Client.WithLogger option and Client.SetLogger method have been implemented. Same applies for the smtp counterparts.

Details can be found in #102 and #115 .

More support for middlewares

With #108, #109 and #117 we provide more access to message parts (like attachments or embeds) for middlewares. Parts can now be gotten, set and deleted by middlewares.

Fix attachment reader consectuive writes

Msg.AttachReader() would not output the attached file after consecutive writes (e.g. a write to a file and then send via Client). In #111 we fixed this behaviour by first reading the io.Reader into memory and then creating a new bytes.Reader, which does support seeking. In the writeFunc we then seek to position 0 after a successful io.Copy. This is probably not the most memory efficient way of handling this, but otherwise we'll have to break the io.Reader interface, which we do not want..

To compensate this, additionally, a new way of attaching/embedding files has been added: Msg.AttachReadSeeker() and Msg.EmbedReadSeeker() which take a io.ReadSeekeras argument instead. These two methods will skip the reading into memory and make use of the Seek method of the corresponding interface instead.

We recommend to make use of the new methods instead, to make the memory footprint low.

Special thanks

Special thanks go to @Karitham, @cvette and @halilylm for reporting bugs and/or providing PRs to address issues. Also big thanks to @james-d-elliott of the Authelia project for providing helpful insights on various issues with the library.

What's Changed

• Set up FreeBSD tests via CirrusCI by @wneessen in Set up FreeBSD tests via CirrusCI #99
• Fork the net/smtp package from Go's stdlib into go-mail by @wneessen in Fork the net/smtp package from Go's stdlib into go-mail #100
• Implement SMTP client debug logging by @wneessen in Implement SMTP client debug logging #102
• Update documentation and copyright headers by @wneessen in Update documentation and copyright headers #103
• Refactor DSN handling from client.go to smtp.go by @wneessen in Refactor DSN handling from client.go to smtp.go #104
• Introducing Msg part deletion by @wneessen in Introducing Msg part deletion #108
• Introduce GetEmbeds() and SetEmbeds() by @wneessen in Introduce GetEmbeds() and SetEmbeds() #109
• Fix Attach/EmbedReader and implement Attach/EmbedReadSeeker by @wneessen in Fix Attach/EmbedReader and implement Attach/EmbedReadSeeker #111
• Go1.20 workflow updates by @wneessen in Go1.20 workflow updates #113
• Update golangci-lint to Go 1.20 by @wneessen in Update golangci-lint to Go 1.20 #114
• Implement Logger interface by @wneessen in Implement Logger interface #115
• Provide more ways for middleware to interact with mail parts by @wneessen in Provide more ways for middleware to interact with mail parts #117
• fix: parsing of ReplyTo with special characters by @cvette in fix: parsing of ReplyTo with special characters #118
• Make golangci-lint happy again by @wneessen in Make golangci-lint happy again #120
• Remove defer from for loops by @wneessen in Remove defer from for loops #122

New Contributors

• @cvette made their first contribution in fix: parsing of ReplyTo with special characters #118

Full Changelog: v0.3.8...v0.3.9

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