poul-list/src, branch master

Add queue for mail processing

2026-05-09T01:27:15Z

Add DB table for queue. It is necessary in case the delivery fails and we'll need to retry. Signed-off-by: Mroik

Fix last touchups on SmtpServer and add test

2026-04-15T02:36:35Z

Fix some mistakes in the SmtpServer implementation and add test. This test is only for the ideal interaction, it doesn't cover all checks for the malformed or out of order commands. This is left for later. Signed-off-by: Mroik

Remove extra String alloc improving memory usage

2026-04-13T04:56:12Z

Signed-off-by: Mroik

Move logging for premature TCP termination

2026-04-13T04:56:12Z

It logs anytime we break out of the loop, therefore logging a connection closed by remote regardless of what happened. Move logging to closed connection check and make it a warn instead of an info. Signed-off-by: Mroik

Add SMTP QUIT command

2026-04-13T04:56:12Z

Signed-off-by: Mroik

Fix reply messages

2026-04-13T04:56:12Z

The replies do not end with . Fix it. Signed-off-by: Mroik

Add a note on email encodings

2026-04-13T04:56:11Z

Leave a note for future devs that the server might receive an email with an encoding different from ASCII or UTF-8. This can be problematic as String accepts only UTF-8 valid strings. In TODO when I say "handle non UTF-8 encodings", I think it would be totally ok to just disregard anything that isn't UTF-8 and return a "rejected for policy" error to the MTA. Otherwise we'll just have to put `encoding_rs` in the mix. Signed-off-by: Mroik

Replace std socket IO with tokio socket IO

2026-04-13T04:56:11Z

Since the TcpListener (and related) operations are blocking, they would prevent other tasks from running by monopolizing CPU time. This should've been done from the start but I'm not used to directly using low level primitives in an async environment as I would normally use a high level library for this, so I forgot. Signed-off-by: Mroik

Do not propagate TcpListener.accept() errors

2026-04-13T04:56:11Z

Errors produced by the socket may not be necessarily fatal, meaning that while a connection might be dropped the process should be able to resume execution as if nothing happened and accept the next connection. Error handling for accept() has been copied from NGINX's [1]. [1] https://stackoverflow.com/questions/76955978/which-socket-accept-errors-are-fatal Signed-off-by: Mroik

Add mail processing scaffolding

2026-04-13T04:56:11Z

After receiving the email we don't want to process it in the same thread as soon as we can, instead we queue it to a MailProcessor. This allows us to be more flexible with the pipeline and reduce the amount of concurrency for the database connection. This also helps with writing possible fences around resource consumption. Signed-off-by: Mroik