similar to greylisting, but not quite the same: with greylisting you would
always reject the first delivery attempt with a temporary failure. with the
hope that spammers won't retry their deliveries. the spams i've been receiving
seem to be quite consistent though. and we would keep rejecting them anyway.
we slow down the spammy connections to waste some of the resources of a
spammer. this may slow their campaigns down a bit, leaving a bit more time to
take measures.
we do the same with connections that have their 3rd authentication failure,
typically password guess attempts.
when we accept a message by a first-time sender, we sleep for 15 seconds before
actually delivering them. known-good senders don't have to wait. if the message
turns out to be a spammer, at least we've consumed one of their connections,
and they cannot deliver at too high a rate to us because of the max open
connection limit.
- make the example commands in the readme more likely to succeed, especially
for people who are not familiar with go and its toolchain.
- improve probability that the correct configuration is generated, especially
the hostname. previously, if the quickstart email address was "some.domain",
and the machine where you ran the quickstart was "myhost", the hostname used
for the configuration was assumed to be "myhost.some.domain". but this is often
not correct, especially when configuring mox to serve mail on a subdomain of an
existing domain. mox will now try to determine the host name by a reverse
lookup of the public ips it found. and it will warn if there are no/multiple
candidates.
based on feedback from erik dubbelboer, thanks!
