Got a strange behaviour
1) Getting mails from specific customer domain abc.com)
2) Specific sender email@example.com has sent mails but same are not received by us.
3) When i check the archive (saviour tool :-)) this mail is available on specific data/time as per sender and is retrieved
4) But this mail is not even in SMTP logs as per original sender date/time
5) what could have caused this mail not delivered / downloaded