Users are not receiving reset password emails

[NakedAlien]

Today there was a switch from phpbb3 to vbulletin. And now users need to reset their passwords to login. But no email is being sent! I tested this myself with two different accounts and no emails arrive. So no one can login because no one can change their passwords. Also I found myself unable to send emails using the email client that came with the hosting. This has never happend before so I'm thinking it could be same issue.
How do I fix this?

[snakes1100]

Unfortunately to truly trouble shoot this issue, you need to tail your maillog.

ie... tail -f /var/log/maillog
cpanel - tail -f /var/log/exim_mainlog
plesk - uses qmail and depending on what plesk you have on the server, its log file could be in one location or another.

You could also try enabling the smtp option in the admincp --> vbulletin options and try that route.

[NakedAlien]

Also now I noticed there are two errors on top of the page while someone tries to get a new password:

Warning: fsockopen() [function.fsockopen]: unable to connect to :25 in [path]/includes/class_mail.php on line 635

Warning: fsockopen() [function.fsockopen]: php_network_getaddresses: getaddrinfo failed: Name or service not known in [path]/includes/class_mail.php on line 635

[Dismounted]

Make sure the mail server address is set correctly and that it is up.

[NakedAlien]

I got it to work now! Was quite simple. I didn't have it on stmp and I had to write localhost to the field. Worked great after that.