othellotech, your right. We did trace the problem however I do believe this belongs in the original thread it was put in, as a feature request.
When mails fail, it would be nice to have a retry option, either automatically or done manually using the utilities menu.
I like WHMCS, I didn't submit a ticket about this because I didn't think it was a problem. What is happening to us is probably what is happening to others with this same problem. The IP that the webserver is using to contact the mailserver for some reason is changing.
Im not going to get into the network configuration aspect of it, obviously it's something we need to resolve on our end. So the reason for the trouble with the mail is the mail is being delayed because the system is using different ip's and some ip's dont have ptr's and our mailservers are configured to check the ptr's. That time necessary to check and return a 0 response is allowing WHMCS to just not send the mail.
Perhaps there is an option in the configuration itself for WHMCS to wait longer before it just gives up sending a message.
So I do apologize for blaming WHMCS as this doesn't appear to be a bug in WHMCS, it appears to be something that could however be resolved by a WHMCS setting.