New to Nagios, need help changing mail server

I am new to Nagios.

Our previous tech just up and left the company and I have been asked to change the mailserver Nagios routes it’s alerts through.

I have been unable to work out what its using to send the mail to the existing mail server.

No sign in Nagios of any 3rd party apps being used to send the mail.

HELP!

check if you have postfix or sendmail or exim running… if not try a search on the forum there are some scripts you can use to send the email to another server.