Identifying which MTA is running

Solution 1:

Easiest way might be to get the PID of what's listening on port 25:

 # sudo lsof -i :25   
 COMMAND  PID USER   FD   TYPE DEVICE SIZE NODE NAME
 master  5664 root   12u  IPv4  13732       TCP *:smtp (LISTEN)

Then find out what that process is:

 # ps p 5664
 PID TTY      STAT   TIME COMMAND
 5664 ?        Ss     0:12 /usr/lib/postfix/master

And I'm running postfix. For sendmail, it looks like this:

 # lsof -i :25
 COMMAND   PID USER   FD   TYPE DEVICE SIZE NODE NAME
 sendmail 3445 root    4u  IPv4  12922       TCP localhost.localdomain:smtp (LISTEN)

Edit

Postfix config is under /etc/postfix , "sudo" might be necessary

Solution 2:

most mail servers will identify themselves

justin@bert ~ % telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 xxxx ESMTP Exim 4.69 Sat, 09 Jan 2010 15:08:05 -0500

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Solution 3:

For your second question, use locate to find master.cf

updatedb
locate master.cf