To send mails, today some tests use msmtp and others our internal smtpc.py.
This works, but msmtp slows down the tests significantly, and smtpc.py
is also not particularly fast, and also has some limitations.
This patch introduces a new SMTP client tool written in Go, and makes
almost all the tests use it.
Some tests still remain on msmtp, mainly for client-check compatibility.
It's likely that this will be moved in later patches to a separate
special-purpose test.
With this patch, integration tests take ~20% less time than before.
Hook output is checked to see if it looks like a header, which includes
the possibility of multi-line headers.
This patch extends the tests to include a multi-line header, to prevent
accidental regressions.
Currently, chasquid exits if any mode (SMTP/submission/submission+tls)
has no addresses to listen on. This means that chasquid must be given
addresses for all three.
While that's generally the expected configuration, there are cases where
users may not want to have all three.
So this patch replaces that fatal error with a warning, and only makes
chasquid exit if there are no addresses to listen on at all.
This patch adds support for TLS-wrapped submission connections.
Instead of clients establishing a connection over plain text and then
using STARTTLS to switch over a TLS connection, this new mode allows the
clients to connect directly over TLS, like it's done in HTTPS.
This is not an official standard yet, but it's reasonably common in
practice, and provides some advantages over the traditional submission
port.
The default port is 465, commonly used for this; chasquid defaults to
systemd file descriptor passing as for the other protocols (for now).
The default INFO logs are more oriented towards debugging and can be
a bit too verbose when looking for high-level information.
This patch introduces a new "maillog" package, used to log messages of
particular relevance to mail transmission at a higher level.
This patch implements a post-DATA hook, which is run after receiving the
data but before sending a reply.
It can be used to implement content filtering when receiving email, for
example for passing the email through an anti-spam or an anti-virus.
