Stale DNS Records

[jvetter]

We are having trouble with a local business emailing us. It started just after we changed our mail filtering service. Here is the bounce back message they get:

Your message could not be sent.
A transcript of the attempts to send the message follows.
The number of attempts made: 1
Addressed To: user@domain.com

Fri, 05 Sep 2008 15:00:02 -0500
Failed to send to identified host,
user@domain.com: 147.202.xx.xx (our old mail filtering ip, 553 sorry, mail relay to user@domain.com prohibited, please authenticate or set up relaying
for 69.66.xx.xx (there mail server ip) unknown (#5.7.1)
--- Message non-deliverable.

Why is there outbound mail pointing at our old mail filtering ip? We are having no other problems with anyone else. I talked to our ISP support and they said, "They could certainly have stale DNS entries on their end that would cause that, as I do show that IP is not any one of your current MX's." Does this sound like it could be the issue? What do I need to tell the company that's trying to send to us?

Thanks.

 

[elgrandeperro]

Did you adjust your TTL before cutting over? I always step it down (1 week, 1 day, 1 hour, 5 minutes) for web servers/ftp/mx records that are time sensitive.

You could ask them to flush their cache (if you know them well).

The other cause is that some unnamed ISPs ignore the TTL and cache answers longer.