Upgraded one of our Incoming Gateways from SmarterMail 13.6.5703 to 15.0.5962 and everything went fine with one solitary exception: AntiSpam RBL & URIBL lookups now take > 5000 ms (up to 20,000 ms) after the upgrade!
I tried reinstalling and then even did a clean install of 15.0.5962 and reconfigured everything from scratch, but no difference.
On 13.6.5703 these RBL & URIBL lookups took @ 36ms (with the slowest being 98ms). And yes, we are using our own DNS Servers. An NSLOOKUP to the same RBLs from a command prompt shows no such latency, and all of our other incoming gateways have these same RBL & URIBL lookups working fine, meaning this is entirely either a .NET 4.5 or SmarterMail issue.
I saw in some other threads that others experienced a similar problem after upgrading to v15 but it resolved itself on it's own, so I let it run over the weekend in this state and unfortunately it never improved.
The problem is that this is a high volume gateway and having a 5-30 min delay in doing AntiSpam checks on incoming email is simply unacceptable to both us and the customer. The spool ends up getting backed up in the thousands because of the AntiSpam checks delay. (Although taking it down for 5-10 minutes to roll-back to v13 or v14 isn't an ideal solution either, but I'm thinking of doing exactly that after peak hours.) Anyone have any ideas of what to try to resolve this?