Somehow lately we are getting lots of spam messages in our inbox, these are not regular spam but almost all mail delivery notifications.
At one point one of our colleagues had about 20.000 of these in her inbox.
We already setup an external spam filter which helps but we still get lots of emails. I also setup spf records, and enhanced several security fetures. Our smtp server is not open relay, and also only accepts smtp connections from certain IPs and only if you authenticate, which makes me believe we have an infected computer somewhere in the network. We run both Mac and PC.
I started investigating and I noticed our smtp message queue to be extremely full with spoofed messaged, see attached file.
I tried to see where these are coming from, or at least who sends these, but I haven't found a way to do this.
I noticed I can only look in the queue and not see any specific details about who send the message, except for a "from" which is obviously bogus.
Is there any way I can see who is sending spoofed mails from my mailserver?
Any help is greatly appreciated.
[Updated on: Tue, 24 February 2015 15:09]
Right click on one of the column headings and make sure that you've selected any user/message source identifiable columns. Not all of them are enabled by default. You can display the sender IP address as well as the From field which should help.
[Updated on: Tue, 24 February 2015 20:11]
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