Don
I have been having this problem also going back at least 1 year here on Detail City, Autopia, Detailers Club And on Meguiar's. I have tired countless time to contact Meguiar's to see if the could tell me if there was a E-mail notification sent to determine if my service provider was scrubbing out E-mails generated from there site....I just gave up. I was thinking the mass E-mails generated by these sites were marked as spam by my service providers soft ware. no one seems to understand the vBulletin program enough to find the answers to solve the problem, or I'm not conveying my question right with out confusing the second party. Either way it was easier to use a different account.
The fix I use today is that I'm using a gmail and have not see any problems with the E-mail notifications since opening this account.
Hope this is enough info for you.
Good Luck