> My server is quite low traffic, but it's been delivering mail reliably. How do I know? When I send mails, there's usually follow-ups.
And when there's no follow-ups, you just assume your mail has been delivered? I recommend actually measuring your deliverability before making claims about it.
> Well either there's a bounce, or some other indicator in the postfix logs (collected by filebeat, with alertings in kibana).
The most common type of problem is that mail is delivered but placed into the spam folder. You will not be notified of this with a bounce or anything in your postfix logs.
> If I'd still be getting blackholed with a "250 delivered" in my logs, then screw it.
This is another type of problem I've encountered. It's rarer than the spam folder, but it happens.
And when there's no follow-ups, you just assume your mail has been delivered? I recommend actually measuring your deliverability before making claims about it.