[CentOS] Tracking down application sending mail in CentOS 7

Fri Jun 25 01:59:16 UTC 2021
H <agents at meddatainc.com>

On 06/23/2021 09:59 PM, Frank Cox wrote:
> On Wed, 23 Jun 2021 21:54:02 -0400
> H wrote:
>> Can anyone suggest how to track down the app so I can reconfigure the mail
>> address?
> And the relevant line(s) in /var/log/maillog are....
Here is an example line:

Jun 25 03:25:40 centos7 postfix/smtp[59252]: 6AB952C03793A: to=<root at aaa.bbb.ccc>, relay=smtp.1and1.com[]:587, delay=1.4, delays=0/0.02/1.2/0.23, dsn=5.0.0, status=bounced (host smtp.1and1.com[] said: 550-Requested action not taken: mailbox unavailable 550 invalid DNS MX or A/AAAA resource record (in reply to RCPT TO command))

aaa.bbb.ccc above is a filler for the incorrect address, in fact a malformed address on the server itself that I need to track down, and, as I understand it, the reason smtp.1and1.com kicks it away.