Mail Notification semi working

Hello!

we are using the latest stable checkmk raw version.
I am currently trying to set up an e-mail based notification system.

I’ve created a 1&1 (ionos) E-Mail Account, so we don’t have to create a new user in our network (ms exchange, active directory) with an e-mail account that has smtp enabled.

After some google research, I decided to attempt postfix.
Trying to send a Test-Mail via Command Line doesn’t work / arrive. So here is the log

Feb 23 11:24:57 checkmk postfix/pickup[2874212]: 777D91BD1: uid=996 from=<mycustomsite>

Feb 23 11:24:57 checkmk postfix/cleanup[3108493]: 777D91BD1: message-id=<20210223102457.777D91BD1@checkmk>

Feb 23 11:24:57 checkmk postfix/qmgr[2874201]: 777D91BD1: from=< mycustomsite@checkmk>, size=452, nrcpt=1 (queue active)

Feb 23 11:24:57 checkmk postfix/smtp[3108496]: 777D91BD1: to=<mytest@email.tld>, relay=smtp.ionos.de[213.165.67.97]:25, delay=0.38, delays=0.01/0/0.34/0.03, dsn=5.0.0, status=bounced (host smtp.ionos.de[213.165.67.97] said: 550-Requested action not taken: mailbox unavailable 550 invalid DNS MX or A/AAAA resource record (in reply to MAIL FROM command))

Feb 23 11:24:57 checkmk postfix/cleanup[3108493]: D9DF11C12: message-id=<20210223102457.D9DF11C12@checkmk>

Feb 23 11:24:57 checkmk postfix/bounce[3108519]: 777D91BD1: sender non-delivery notification: D9DF11C12

Feb 23 11:24:57 checkmk postfix/qmgr[2874201]: D9DF11C12: from=<>, size=2520, nrcpt=1 (queue active)

Feb 23 11:24:57 checkmk postfix/qmgr[2874201]: 777D91BD1: removed

Feb 23 11:24:57 checkmk postfix/local[3108521]: D9DF11C12: to=< mycustomsite@checkmk>, relay=local, delay=0, delays=0/0/0/0, dsn=2.0.0, status=sent (delivered to mailbox)

Feb 23 11:24:57 checkmk postfix/qmgr[2874201]: D9DF11C12: removed

But on the other hand, I set up in checkmk the notification on the created site, using From: Address the E-Mail Account I’ve added into the “/etc/postfix/sasl_passwd”-file, use my checkmk-user with my own e-mail, I receive actual alerts (e.g. wsus-service down).

Now the question, what is wrong, and do I even need the postfix configs? It’s mentioned in the checkmk docs…

Thanks in advance,
Kind regards,
Fab

Hi @Fabsi

Well - if I understand your posting correctly - strictly speaking, you don’t have a “CheckMK” question, but a “postfix” one. This URL may be a good starting point:

http://www.postfix.org/STANDARD_CONFIGURATION_README.html

Other than that, I’m sure you can find help for your issue in a more appropriate forum. That said: I believe that the notifications do work for you, because most Linux distributions set up a “nullclient” MTA per default.

HTH,
Thomas