I manage a small VPS and have noticed in the last few days that email usage has blown way out of the norm. What usually is only a few dozen has instantly shot up to our relay-limit of 1,000/day. The OS is CentOS and I'm running Simple Control Panel to assist me in setting up email addresses and domains.
How can I determine which account, on which domain, is sending/receiving all of these emails?
Resolving the issue:
As suggested in the accepted answer below, I ran the
mailq command and was immediately flooded with a seemingly never-ending list of email addresses. Finally forcing the load to abort with CTRL+Z, I was able to discern which account all of the email addresses were coming from:
004F1C3D5B0* 22534 Fri Feb 11 12:27:48 firstname.lastname@example.org SOME.EMAIL@DOMAIN.COM ANOTHEREMAILFTW@DOMAIN.COM THIRDADDRESS@NEWDOMAIN.COM 4RTHEMAIL@SAMPLEDOMAIN.COM ...
This is an extremely small sample of what filled my screen. From this, I was able to determine that the lowercase email on the first line must be the address sending/receiving all of these emails.
I hope I'm not mistaken.