The error the sender receives is Remote host said: 557 The server encountered an error while processing this message. Please retry later.

 

That "557" is fatal - sending servers do not retry. And we end up looking like chumps.

 

Can anyone shed light on why an internal processing error would generate a permanent failure code instead of a temporary "4xx" error so emails could be re-queued by the sending system?

 

This issue is pretty random. I'll see it in a logfile along with hundreds of successful deliveries. Here's the SpamFilter excerpt of the event that triggers that 557 error...

 

03/11/10 05:16:54:265 -- (644) Connection from: x.x.x.x  -  Originating country : United States
03/11/10 05:16:55:171 -- (644) Received MAIL FROM: <sender@senderdomain.com>
03/11/10 05:16:55:249 -- (644) Received RCPT TO: recipient@example.com
03/11/10 05:16:55:265 -- (644) Resolving x.x.x.x - mail.senderdomain.com
03/11/10 05:17:02:515 -- (644) - SPF analysis for senderdomain.com done: - none
03/11/10 05:17:02:515 -- (644) Mail from: sender@senderdomain.com
03/11/10 05:17:23:515 -- (644) - MAPS search done...
03/11/10 05:17:23:515 -- (644) RCPT TO: recipient@example.com accepted
03/11/10 05:17:23:874 -- (644) Checking SFDC
03/11/10 05:17:24:218 -- (644) SFDC - Added x.x.x.x - Response: Error=0
03/11/10 05:17:24:234 -- (644) Exception occurred during RECEIVEMESSAGE: ( 1 2 2b 3 3a 4 5 6 7 8 9 11 12 13 15 16 17 18 18b 19 20b 20c 29 30 31 32 111) Access violation at address 00413B4E in module 'SpamFilterSvc.exe'. Read of address 00000005 --
03/11/10 05:17:24:312 -- (644) Disconnect

 

If we restart the service, things are smooth again for a few days. But this random rejection business is difficult to explain to customers. Any help greatly appreciated.