sending alot email gives 500 error

[joey3002]

I followed this guide:
http://www.howtoforge.com/perfect-se...10-ispconfig-3

everything is set up and working perfectly.

The issue I am having is one of my scripts I run, sends a large amount of emails. It also has attachments that vary in size. If I send 25 emails, its not a problem.

However, when I use my system and put a checkbox in say 500 and hit send, it runs for awhile and then gives:

ERROR 500 - Internal Server Error!
The following error occurred:
The requested URL caused an internal server error.
If you get this message repeatedly please contact the webmaster.

I am sure its timing out or something. What should I be looking for to ensure that the email will go out and just queue up and work through it till its done?

thanks all