Mail problems

I have an annoying problem with the mail() function intermittently taking a long time to execute. I checked the list archive and it was suggested to put the -q switch on the command line, which, according to the article, means that sendmail will queue the mail rather than sending it immediately. I did that so the sendmail command line was /usr/sbin/sendmail -tq (The -t was there by default, so I left it there.) This did not work at all, in fact the mail function executed quickly but no mail was sent. I have not checked for a return error code. However this conflicts with the sendmail documentation. According to the book, the -q switch tells sendmail to process its queue and exit, and says nothing about just queueing the mail. Reading further through the book, I find this option: -ODeliveryMode=background so the sendmail command line in php3.ini is now /usr/sbin/sendmail -t -ODeliveryMode=background which tells sendmail to fork a new process to deliver the mail and exit immediately. This worked fine, it was fast, the mail was delivered and I was happy -- for about an hour, then it became slow again. It takes up to 2 minutes to send an e-mail, and I have users registering 4 or 5 times because they think the 'puter didn't hear them the first time they submitted the form. When I check the sendmail queue, it's empty. WHen I run a top during this long waiting period, sendmail doesn't even appear in the list of active processes. However I have checkpointed the script extensively and know with 100% certainty that it's hung up at the mail function. Any clues would be appreciated. Jeff Wolkove