mail() problems

I've been using the built-in (?) 'mail()' function quite successfully so far (ie, a couple of years) and have not had need to seek an alternate. That said, I now have to ask the group if there are known cases of intermittent success with this tool. I have a pretty good working template for handling emails with a piped script that sends it results to a std mailbox for review after the script does it thing. I have several (3-4) scripts linked to mailboxes that work successfully every time, meaning that my db gets updated and the emails get sent. Recently I built a new mailbox, made a new script from my template and began testing. At first (after clearing out all the syntax errors) it worked successfully but then after a dozen or so tests I stopped getting the emails. Now it gets weird. Sometimes the script doesn't seem to run at all since my db doesn't get updated nor do I receive an email. Other times the db does get updated but I still get no email. I have debugged and debugged and placed incremental 'send email' steps throughout my code and still no emails come back. But then all of a sudden it works! My hosting co. says there is no problem with my email accounts and no errors showing, nor do I have any error logs that show anything. It's been about 4 days now and I am at a loss to explain it. Could it be possible that php or mail() is truly buggy and tempermental? FYI -my host is running mysql 5.5.37(cli) with php 5.4.31 on apache 2.2.7