Newsletter Sending Hangs

Hello,

We're trying to send a newsletter we've sent before, however it hangs before reaching the end of the list. We've attempted three restarts, but it continues to stop at various locations in the list.

I have checked with our hosting provider that we're not violating the message / hour limit (750) are we are not. We also use the newsletter throttling plug-in to ensure we don't exceed 700 / hr. Last failure I had it throttle down to only 325, and still it failed. Hosting provider sees no violations in their logs.

Are there any logs in Zen-cart I can check. I looked in the /cache folder and found nothing there. I found no /log folder. Do I need to turn logging on? I don't find options for such in the admin interface.

Thanks for the help.

Greg