SASL username not exist (spammer)
Have some problem with email.
In log file I find this:
Feb 17 18:38:25 srv postfix/smtpd: connect from mail.domain.com [220.127.116.11]
Feb 17 18:38:25 srv postfix/smtpd: C4E2D4F03A3: client=mail.domain.com [18.104.22.168], sasl_method=LOGIN, sasl_username=srv3_test
Feb 17 18:38:25 srv postfix/cleanup: C4E2D4F03A3: message-id=<firstname.lastname@example.org>
Feb 17 18:38:25 srv postfix/qmgr: C4E2D4F03A3: from=<email@example.com>, size=1185, nrcpt=1 (queue active)
Feb 17 18:38:25 srv postfix/smtpd: disconnect from mail.domain.com [22.214.171.124]
it is repeat every 2-5 min. I have mail server mail.domain.com and hosting panel ISPConfig. I had user srv3_test, but its deleted.
Why this user have sasl login?
It is spammer or something else?