I'm running GroupWise 8 on Netware. I'm filtering our inbound email through MX Logic. When I leave my firewall set such that any SMTP server on the Internet can connect to my server, all is fine. However, whenever I set my firewall to allow only MX Logic SMTP servers to connect to my server, I have problems. Most email still comes in, but some gets bounced back to the sender with the following error:

A temporary error occured while delivering to the following address(es):
<farren@aibonline.org>: 451 All MX servers are unavailable for domain aibonline.org
I will continue trying to send the message until it is delivered
or expires.

After a few days of getting the 'temporary error occured' messages, the sender typically gets a final error stating that the message could not be delivered and 'I've quit trying to send it'...

I opened a ticket with MX Logic support. They pulled a log file and said it was a problem on my end:

[2010-01-15-10:43:22] [I] (Accept) Accepted INBOUND Job from (
[2010-01-15-10:43:22] [I] (MAIL) From:<farren@computershed.com>
[2010-01-15-10:43:22/c52e1b90/6008011.00-072] [I] (RCPT) RCPTTO: <farren@aibonline.org>
[2010-01-15-10:43:22] [I] (DATA) F[044]<- 354 Start mail input;
[2010-01-15-10:44:07] [I] (Worker) Connection failed ( 45001 msecs (NOCONN)
[2010-01-15-10:44:07] [I] (Worker) Connection timeout ( 0 msecs (NOCONN) 0 timeout

Looks like there's a 45 second time out happening on my end, but I don't know why or where...

I fail to understand why everything works fine when the firewall is open to the world, but doesn't work fine when I restrict my firewall to just MX Logic. Any suggestions greatly appreciated.