Postconf: https://pastebin.com/vTVn2UMr
Doveconf: https://pastebin.com/nEpZrpzB

all my logs from mail.(warn,err,info,log): https://pastebin.com/ccEVUqyd
my messges log: https://pastebin.com/cXaEBmcH

I'm not sure if you meant this about dict_nis_init but I've done what's explained here: https://unix.stackexchange.com/questions/244199/postfix-mail-logs-keep-showing-nis-domain-not-set

On 19/07/2020 21:05, Alexander Dalloz wrote:
Am 19.07.2020 um 10:20 schrieb Nils:

Here are my configurations:
Postfix main.cf: https://pastebin.com/S17jWDQd
Postfix master.cf: https://pastebin.com/W0nynZG6
dovecot.conf: https://pastebin.com/tMD90Znn

Please provide your configurations processed by the tools postconf and doveconf.

This is what my server logs (mail.info, mail.warn) tell me:
root@bgrsld-mail0:~# tail /var/log/mail.info
Jul 17 18:22:08 bgrsld-mail0 postfix/submission/smtpd[8472]: improper command pipelining after EHLO from unknown[192.168.2.110]: QUIT\r\n
Jul 17 18:22:08 bgrsld-mail0 postfix/submission/smtpd[8465]: disconnect from unknown[192.168.2.110] ehlo=1 quit=1 commands=2
Jul 17 18:22:08 bgrsld-mail0 postfix/submission/smtpd[8472]: disconnect from unknown[192.168.2.110] ehlo=1 quit=1 commands=2
Jul 17 18:24:59 bgrsld-mail0 postfix/submission/smtpd[8485]: warning: dict_nis_init: NIS domain name not set - NIS lookups disabled
Jul 17 18:24:59 bgrsld-mail0 postfix/submission/smtpd[8485]: connect from unknown[192.168.2.110]
Jul 17 18:24:59 bgrsld-mail0 postfix/submission/smtpd[8485]: improper command pipelining after EHLO from unknown[192.168.2.110]: QUIT\r\n
Jul 17 18:24:59 bgrsld-mail0 postfix/submission/smtpd[8485]: disconnect from unknown[192.168.2.110] ehlo=1 quit=1 commands=2
Jul 17 18:28:19 bgrsld-mail0 postfix/anvil[8473]: statistics: max connection rate 2/60s for (submission:192.168.2.110) at Jul 17 18:22:08
Jul 17 18:28:19 bgrsld-mail0 postfix/anvil[8473]: statistics: max connection count 2 for (submission:192.168.2.110) at Jul 17 18:22:08
Jul 17 18:28:19 bgrsld-mail0 postfix/anvil[8473]: statistics: max cache size 1 at Jul 17 18:22:08
root@bgrsld-mail0:~# tail /var/log/mail.warn
Jul 17 18:21:50 bgrsld-mail0 postfix/postfix-script[8290]: warning: symlink leaves directory: /etc/postfix/./makedefs.out
Jul 17 18:22:08 bgrsld-mail0 postfix/submission/smtpd[8465]: warning: dict_nis_init: NIS domain name not set - NIS lookups disabled
Jul 17 18:22:08 bgrsld-mail0 postfix/submission/smtpd[8472]: warning: dict_nis_init: NIS domain name not set - NIS lookups disabled
Jul 17 18:24:59 bgrsld-mail0 postfix/submission/smtpd[8485]: warning: dict_nis_init: NIS domain name not set - NIS lookups disabled

There is no SMTP AUTH in the log. Provide the logs from a connection where your MUA tries to auth.

And fix the dict_nis_init thing. See alias_maps.

Alexander