Reason: 4.4.0 - Other network problem ('000', ['[Errno 60] Operation timed out']) []

[noraarellano]

Hello,

Im having problems when some domains send emails to my organization.

When I check the logs I notice this error:

09 Feb 2016 13:40:17 (GMT -06:00)	Message 113196344 to XXXX@mydomain.com.mx pending until Tue Feb 9 13:51:06 2016 as per bounce profile Default.
09 Feb 2016 13:51:08 (GMT -06:00)	SMTP delivery connection (DCID 38607692) opened from Cisco IronPort interface A.A.A.A to IP address B.B.B.B on port 25.
09 Feb 2016 13:51:08 (GMT -06:00)	(DCID 38607692) Delivery started for message 113196344 to XXXX@mydomain.com.mx.
09 Feb 2016 13:52:28 (GMT -06:00)	(DCID 38607692) Message 113196344 to XXXX@mydomain.com.mx delayed. Reason: 4.4.0 - Other network problem ('000', ['[Errno 60] Operation timed out']) []
09 Feb 2016 13:52:28 (GMT -06:00)	Message 113196344 to XXXX@mydomain.com.mx pending until Tue Feb 9 14:27:39 2016 as per bounce profile Default.
09 Feb 2016 14:27:41 (GMT -06:00)	SMTP delivery connection (DCID 38609605) opened from Cisco IronPort interface A.A.A.A to IP address B.B.B.B on port 25.
09 Feb 2016 14:27:41 (GMT -06:00)	(DCID 38609605) Delivery started for message 113196344 to XXXX@mydomain.com.mx.
09 Feb 2016 14:29:01 (GMT -06:00)	(DCID 38609605) Message 113196344 to XXXX@mydomain.com.mx delayed. Reason: 4.4.0 - Other network problem ('000', ['[Errno 60] Operation timed out']) []
09 Feb 2016 14:29:01 (GMT -06:00)	Message 113196344 to XXXX@mydomain.com.mx pending until Tue Feb 9 15:29:01 2016 as per bounce profile Default.
09 Feb 2016 15:29:01 (GMT -06:00)	SMTP delivery connection (DCID 38612678) opened from Cisco IronPort interface A.A.A.A to IP address B.B.B.B on port 25.
09 Feb 2016 15:29:04 (GMT -06:00)	(DCID 38612678) Delivery started for message 113196344 to XXXX@mydomain.com.mx.
09 Feb 2016 15:30:24 (GMT -06:00)	(DCID 38612678) Message 113196344 to XXXX@mydomain.com.mx delayed. Reason: 4.4.0 - Other network problem ('000', ['[Errno 60] Operation timed out']) []
09 Feb 2016 15:30:24 (GMT -06:00)	Message 113196344 to XXXX@mydomain.com.mx pending until Tue Feb 9 16:30:24 2016 as per bounce profile Default.

Apparently my Exchange is kind of rejecting the connections but this doesnt happen with any other domains, until today I only detected 2 domains with this behavior.

The domains pass through Whitelist policy in HAT configuration

Someone had this problem in the past?

Thanks in advance for your help!

[martin.eppler]

Hello,

do you block ICMP traffic? It looks like the MTU size upon message delivery is too high and the "Need fragmentation" Response (ICMP Type 3 code 4) is suppressed when ICMP traffic is blocked.

From the log snippet I'd assume that an SMTP session can be established and the first chunk of the mail message is sent by the ESA:

(DCID 38612678) Delivery started for message 113196344 to XXXX@mydomain.com.mx

However, this first chunk does not get an ACK back from the receiving end and needs to be retransmitted. As the retransmissions are not successful either, the appliance times out on delivery:

(DCID 38612678) Message 113196344 to XXXX@mydomain.com.mx delayed. Reason: 4.4.0 - Other network problem ('000', ['[Errno 60] Operation timed out']) []

By setting up a packet capture on the appliance for the given destination IP address you can verify if there is indeed no reply back from the receiving end.

Best regards,

Martin