Question about Mail function time out

Sorry if this shows twice. I originally posted it with Mozilla and forgot that this newsgroup server seems to ignore postings from it. This one is posted from IE. I've got a mail function script that occasionally terminates midway while sending out about 600 emails. The symptoms point to the "max_execution_time" [set for 30]. Two questions: Are their typically any other settings that I need to check. [e.g., session.cache_limiter session.cache_expire] What's the best approach to resolving the problem? Should I get the web host techs to change the php.ini settings? Or, should I modify my script with "set_time_limit()" ? Thanks......