After a couple of support to and fros, I've discovered that our spam filter (TrendMicro Hosted Email Security) is blocking all email alerts from WebRoot, due to a 'dynamic-like' reverse DNS.
The IP/rDNS in question is;
I can understand where Trend are coming from - it doesn't exactly *look* like a standard rDNS for a mail server. I know that for most of the mail servers I configure I have to put a proper rDNS in place otherwise certain MTA's will reject mail.
I've been told that it's not possible for there to be a proper rDNS put in place, as it's in the Amazon AWS - yet I know other places don't have this issue.
Would it be possible to put this on the 'To Do' list?