from http://dimmeria.com/node/1

Step 6a exim4 – outgoing mail

So I thought drupal was set up right. Wrong. My friend tried to create an account, and he never got emailed his password. wtf, mate? Debian installed exim4 for me automatically when I installed – but it was not configured properly. Here is how you configure exim4 on debian so that it will work with drupal (and should work with everything else too). At the command line, run: dpkg-reconfigure exim4-config Go through the configuration script. Your setup may vary from mine. Here are the steps I took:

1. Do not break up the configuration file into smaller files – why make things more complicated for myself?
2. “internet site; mail is sent and received directly using SMTP”
3. mailname=”dimmeria.com”
4. IPs to listen on =”127.0.0.1:192.168.0.x” where x is the last digit of my LAN ip. eg 192.168.0.5
5. other final destinations = blank
6. relay mail for domains – blank
7. Relay mail for local machines – 192.168.0.0/24 (meaning 192.168.0.[1-255])
8. Dial-on-demand: this is only necessary if you don’t have a constant internet connection – you’ll probably want to select no

Finally, do a
update-exim4.conf
/etc/init.d/exim4 restart