Some messages deferring.

[Diluted]

Hi.

I switched to Zimbra this weekend, and I am having a strange issue.

Some of my outgoing emails are deferring, saying the connection is timing out. I have checked the domain MX records for the domains that these emails are being sent to, and in every case, the IP address that shows in the deferred mail notification (mousing over the deferred mail in the Manage Mail Queues panel) is the IP of the domain name, not the MX of the domain.

I have a split DNS setup, with an outside MTA receiving mail and routing them to Zimbra, and outgoing mail going out directly from the Zimbra server.

for example: a message sent to XXXXX@yahoo.com is deferred with the message: connect to yahoo.com[66.94.234.13]: connection timed out

a 'dig yahoo.com' returns:
;; ANSWER SECTION:
yahoo.com. 300 IN A 66.94.234.13
yahoo.com. 300 IN A 216.109.112.135

and a 'dig mx yahoo.com' returns:
;; ANSWER SECTION:
yahoo.com. 7200 IN MX 1 e.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 f.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 g.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 a.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 b.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 c.mx.mail.yahoo.com.
yahoo.com. 7200 IN MX 1 d.mx.mail.yahoo.com.

;; AUTHORITY SECTION:
yahoo.com. 172800 IN NS ns2.yahoo.com.
yahoo.com. 172800 IN NS ns1.yahoo.com.
yahoo.com. 172800 IN NS ns3.yahoo.com.
yahoo.com. 172800 IN NS ns4.yahoo.com.
yahoo.com. 172800 IN NS ns5.yahoo.com.
yahoo.com. 172800 IN NS ns6.yahoo.com.
yahoo.com. 172800 IN NS ns8.yahoo.com.

;; ADDITIONAL SECTION:
e.mx.mail.yahoo.com. 1800 IN A 216.39.53.1
f.mx.mail.yahoo.com. 1800 IN A 68.142.202.247
f.mx.mail.yahoo.com. 1800 IN A 209.191.88.247
g.mx.mail.yahoo.com. 1800 IN A 206.190.53.191
g.mx.mail.yahoo.com. 1800 IN A 209.191.88.239
a.mx.mail.yahoo.com. 1800 IN A 209.191.118.103
b.mx.mail.yahoo.com. 1800 IN A 66.196.97.250
c.mx.mail.yahoo.com. 1800 IN A 216.39.53.3
c.mx.mail.yahoo.com. 1800 IN A 68.142.237.182
d.mx.mail.yahoo.com. 1800 IN A 216.39.53.2

So you can see, it's trying to send the email to the main A record for yahoo.com and not the MX.

Anyone have any ideas?

[dvb]

If you telnet to port 25 on any of Yahoo's mail servers, you will get random "temporarily deferred" messages. This is supposedly their approach to fighting spam.

What I have read is that they feel that legitimate servers will retry, while spam zombies will simply move on to the next victim. If true, it's an interesting approach.

Dave

[Diluted]

Thanks for the suggestion.

Actually, we are running a greylist that does exactly that. If you have never contacted our mail server before, it tells you it's too busy to respond and makes you wait. Seems to reduce the number of spams that come through.

In any case, It ended up being a DNS problem. We had to make sure all of our internal records had the right name for the zimbra server, which they didn't.


It's all working now.

[dvb]

What Yahoo is doing doesn't seem to be greylisting in the usual sense, as the deferral is seemingly random (not just the first connection in a given time frame) and occurs before the connecting server has any chance to pass Yahoo sender/recipient info.

In any event, I'm glad you solved your problem.

Dave