I generally use this command like this:
[blah@blah ~]$ mailq | grep mailq.com
D454790906 1754 Wed May 12 22:06:56 firstname.lastname@example.org
8DAC990C91 1778 Wed May 12 22:22:53 email@example.com
53E2D909CD 1663 Wed May 12 19:21:38 firstname.lastname@example.org
51E7690711 1890 Wed May 12 21:52:13 email@example.com
6FFDA90F07 1258 Wed May 12 23:19:26 firstname.lastname@example.org
Here i get the information i need but only on the domain name.
In a SMTP id i can read a e-mail header and i want to get a list og all the e-mails a certain ip-addresse has sent out.
Then i can go and do:
sudo postcat -q 53E2D909CD
and see this line: Received: from 126.96.36.199 (188.8.131.52 [184.108.40.206.])
so when for me it seems like i could do the same on the ip.