Messaging Gateway

Hello,

We have SBG 8.0.3-11 and it is working well except that there is one domain to which we cannot send email. That domain is receiving email from others and we are sending and receiving to others without any issues.  I can send mail from an external ISP to this domain.
 

The answer in the delivery queue is first "no MXs available for this domain at present" then "450 4.4.1 [internal] Connection timed out"

I can do a DNS lookup for the domain on the SBG without any issue and both the A and MX record are their instantly.  I have flused the DNS on the gateway.  I can manually (telnet) send email from the same subnet without a problem to this domain.

The IT people at that domain can see no problem.  Our ISP can see no problem in their DNS.  They have not blacklisted us.

Can anyone offer a suggestion as to why this one domain should fail when mail is send from our mail server?

In anticipation of a break through ...

 - Neil

Hi Neil,

Please provide more details by answering the following questions:

Does any mail gets delivered to this domain thru SBG?

Does the mail that gets successfully delivered to this domain is a small mail without any attachments?

Does flushing the queue causes the mail to be delivered?

Does the error message change for the same message when you flush the queue?

Does the mail tha gets stuck in the delivery queue with "450 4.4.1 [internal] Connection timed out" contain attachments?

What is the size of the message that gets stuck in the delivery queue?

How long have you been having this issue?

How many SBG boxes you have?

What is the speed of your internet connection?

The issue could be due to network problems or the recipient end.  In any case, a copy of the message exported from the delivery queue, a packet capture at the time delivery queue is flushed, and a debug level maillog are required to proper troubleshoot this issue.

So it would be best to open up a support ticket.  If you do so, please mention this forum thread and let the support agent know that I have requested the support ticket to be opened.

Regards,

Adnan

Hi Adnan

Does any mail gets delivered to this domain thru SBG? - No, but all other incoming and outgoing mail is fine.

Does the mail that gets successfully delivered to this domain is a small mail without any attachments? - With or without attachments it still does not go.

Does flushing the queue causes the mail to be delivered? - No

Does the error message change for the same message when you flush the queue?  - No

Does the mail tha gets stuck in the delivery queue with "450 4.4.1 [internal] Connection timed out" contain attachments?  - Some have some have no attachments

What is the size of the message that gets stuck in the delivery queue? - Very small - a few lines of text only.

How long have you been having this issue? - One week

How many SBG boxes you have? - 1 virtual device

What is the speed of your internet connection? - 2000/384 - There is some bandwidth management guaranteeing 15% and max at 35%

The issue could be due to network problems or the recipient end.  In any case, a copy of the message exported from the delivery queue, a packet capture at the time delivery queue is flushed, and a debug level maillog are required to proper troubleshoot this issue. - Can you tell me how to get the debug log to see what is happening when it tries to deliver?  Is there a step by step log that shows the domain rejecting the mail message?

I have not yet opened a ticket - I would like to look at a detailed log first.

Regards,

 - Neil

Is this a route problem on the SBG config?

Have you tried telnet <ip> 25 from the SBG box?
Does a traceroute to the IP work?

Traceroute works from the SBG device just fine.  nslook also works fine.

I can telnet from the same domain to mail.. without a problem and send an email massage that way.

It is only SBG that will not send the mail to this domain.

 - Neil

Is the domain in your Protocols / Domains list and marked as "local"?  That would force inbound delivery.

Turn MTA logs to debug for a bit and check /data/logs/maillog for details.  (as support login)

Hi,

The domain is not in the Domains list at all.

I have looked at the debug logs but I can't see anything yet.  I may have to log a case I think,

Hi Neil,

Yes, at this point opening up a support ticket and have them look at the packet capture is the best option.

Regards,

Adnan

Hi Adnan,

Don't ask me how or why, but it is suddenly working again.  Beats me, but for now, case closed.

Thanks for your assistance regardless.

 

You are welcome.

OK, I am not going to ask because that basically confirms my earlier assessment: "The issue could be due to network problems or the recipient end."  So most likely, the recipient end has fixed itself, if you did not change anything at your end.  If you do find out the EXACT cause, please share.

Thanks for the feedback.

Regards,

Adnan