Some one is sending spam through my mail server (sendmail) how can I trace his IP.?

Answer 1

The IP that is sending spam is probably connection to a machine that was hacked/zombied -- you need to configure your mail server properly so it only accepts connections from within your domain or require username/password authentication.

Answer 2

Not really... the problem is that spammers generally use public WiFi spots and/or foreign servers to send e-mails. Since sendmail is easy to implement on just about any laptop, spammers can setup shop temporarily from just about anywhere... tracing their IP address will more than likely result in a dead end.

Despite that, there are many Spam blockers out there that intelligently identify spam messages based on content... so your best bet is to find a good spam blocker.

See link for more info.

Answer 3

log into your email account - look for the Options section
in there look for

long header / short header

chances are your short header is enabled
what you want to do is enable the long header
once you have enabled it
click apply or save changes (you may have to scroll down to the bottom of the page to find the apply / save changes)

enabling the long header - opens the full headers and will show all their information (IP address, who their IP server is etc)

Answer 4

If they are sending it from your server, you obviously have it configured as an open relay. You must set it to only accept from your own local network, or require authentication if from outside.