Ex 07: Messages Delayed

[TechieSooner]

Straight and to the point: messages to a domain are delayed.

In the outbound queue the error shows that the "Primary Target responded 421 4.2.1 Unable to Connect"....
Note that responded part, seems to verify comms work.

HOWEVER I cannot do a "telnet their.ip.here 25"- connect failed.

I can send mail to other domains so I know firewalls aren't the issue here.


Any pointers? As with most Message Delivery errors this seems to be an issue with their server however I can't prove that. I suspect they might be rejecting it due to a blacklist or something (I got on a blacklist and was removed two weeks ago).

What's crazy is the "Primary Target Responded" yet I can't telnet to it...

 

[YeOldeStonecat]

Do they have a mail host in between...like postini/appriver/mxlogic? Or does this recipient receive e-mail directly?

 

[Protoform-X]

Restart all of the Exchange services.
Clear your DNS cache, flush DNS on the mail server.

Open a command prompt on the Exchange server:

Type: nslookup <enter>.
Type: set type=mx <enter>
Type: The domain name of the receiving party with no prefix <enter>

Here's an example output:

Default Server:  server.domain.local
Address:  xxx.xxx.xxx.xxx

> set type=mx
> domain.com
Server:  server.domain.local
Address:  xxx.xxx.xxx.xxx

domain.com     MX preference = 10, mail exchanger = mail.domain.com
mail.domain.com        internet address = xxx.xxx.xxx.xxx

Make sure an MX record is returned. If not, you either have a DNS problem, or the MX record doesn't exist.

 

[XOR != OR]

Keep in mind that 4.2.1 indicates an SMTP failure anywhere along the message's route; the primary, relays or destination. So the "target" server in this case may be yours ( reporting on it's failure to contact the next upstream smtp server )

As mentioned, get the MX record and try telneting to port 25. If it doesn't work, then you know that's what's going on. Could also be the blacklist you found yourself on a couple weeks ago.