you need to have a MTA set up properly.
Gimp uses sendmail to send emails.
You can try in a terminal to send an email to yourself and see if it works :
Code:
sendmail me@myhoster.com <push enter>
Just a test message <push enter>>
. <push enter, mail should get send>
The . (point) on a line itself is important to tell sendmail to send the mail.
By the way it is better to install e.g. postfix and configure it in a way that it would relay the mail to your hosters smtp server, as most mailserver refuse to talk to sendmail if you are on dynamic IP (like ADSL) or you don't have a proper reverse DNS record for your IP .
There is a thread about htis here (but it doesn't say much more) :
http://www.gimpusers.com/forums/gimp...-isn-t-working