How to troubleshoot forum email?

Hi,
Since moving to a linux server the forum email does not work anymore. I tried both options, fill in the field with the my provider's smtp server and leave it blank.

I get no error messages and no mail is sent.

I prefer the smtp server because I'm not sure sendmail is setup ok on the server. Although when I use the commandline and 'mail' I can send mail allright.

Where should I look for error messages?

Thanks.

Edit: never mind, it started working...