[systemd-devel] exim4 only queues mails sent by systemd service

[Reindl Harald]

Am 24.09.18 um 22:07 schrieb Dan Nicholson:
> This is exactly what exim does when run via sendmail (which mail and
> mutt likely use behind the scenes). I had a very similar setup to the
> OP using exim on one of our servers and was perplexed why the queue
> wasn't being flushed immediately. Here's what I wrote our git history:
> 
>     I had naively thought that sendmail used SMTP to send a mail to the
>     local MTA. That's actually not the case for either exim or postfix,
>     which use internal procedures to queue and send the mail. Normally
>     that's not a problem except when sendmail is run by a systemd service.
>     Then the way that processes are spawned to queue and send the mail have
>     to match the service type. In the case of exim, the sending process
>     actually forks from sendmail, which systemd kills before it can run if
>     the service type is set to oneshot.

and be happy about it!

other than with the dumb native  "sendmail" you don't lose mails just
because the service won't start for whatever reason

see what happens otherwise

https://www.reddit.com/r/vmware/comments/7mmh3o/vcenter_server_appliance_65_update_1cd_email/

you lose alert mails just because that idiotic configuration was wrong,
with postfix after you got it starting again you get all your
system-mails in the meantime submitted with the "sendmail-interface" aka
maildrop