521 Server does not accept mail

[BiggerDon]

(000B099C) 521 Server does not accept mail
Hi Everyone.

I am running Exchange 5.5 SP3 on NT 4.0 SP6. As of three days ago I get this message from any user trying to email one specific domain. My services don't end and I have recycled them with no improvement. I haven't seen this particular error list here. I've been in touch with the destinations IT department and we can talk to each other via telnet and can send manual emails using telnet so it's not a spam or blacklist issue. Yesterday, one user was able to get a message through but I tried minutes later and no luck! Any ideas?

Thanks DJ

 

[BiggerDon]

Ok I guess I can answer my own post. Turns out to be a DNS error for the destinations email host. Just thought I'd pass it along in case anyone else gets the same error.