I suspect the problem runs deeper.
The IP 96.31.76.198 is listed on three blacklists:
all.spamrats.com
noptr.spamrats.com
b.barracudacentral.org
I'm most familiar with barracuda. Many companies use Barracuda spam appliances to front end their mail servers. Our hosting provider for Conceptaquatics.ca seems to use spamrats.com - My guess is that it's part of a group of RBLs rather than programatically configured, but the end result is the same. We are not getting email notifications.
You can run a quick check here:
http://www.barracudacentral.org/lookups/ip-reputation
I checked some of the other address in the 96.31.76.194/27 address space and many of them are listed on various RBLs. Some of them are listed on many. Fortunately, not all of them are listed.
96.31.76.221 seems to be clean. I stopped checking once I found one that was not listed. A quick fix would be to change the IP for outgoing mail to .221
- Brad