Hi Emanuel,
There are two cases you need to check.
Case 1 :
Check the configuration @ your mailhost and ensure that your mailhost is able to send e-mails. Just execute the command "telnet 25" and check whether your
mailhost is connected.
Case 2 :
If case1 passes, then probably it is a time factor and you need wait for 15 minutes. Event daemon reloads the new global options (the new SMTPServerName) once in every 15 mins. So, you should at least wait for 15 mins after making a change at your mail server field. Otherwise, you can use service stop/start which invokes the DFM to use the newly configured address for mail exchange.
Regards,
Saravanan M