have you established the cause of the problems? I haven't read the thread ^
what mailserver are you using?
is this an 'ip' related issue? i had a similar problem with my forum and basically what happened is someone hacked into our mailserver and was sending spam from our 'ip' effectivly, then the ip was blacklisted.... ....some people recieved emails, some didn't?
if i try changing my email agress registered on here do you think it will work?
mIKe