Software

Ask something
Discussion Locked

421 Service not available

0 helpful
18 replies

by dpotter555 1 view

Closed to new repliesThis discussion is closed. It stays readable, but it takes no new replies.
I am running Exchange 5.5 on an NT machine. In the 'outgoing messages awaiting delivery' queue for the internet mail service there are many emails (32 right now)stuck in there and they are all going to the AOL domain. The details button says "421 SERVICE NOT AVAILABLE. I know these email addresses are valid, but when they aren't delivered within 4 days, the administrative returned message in the senders mailbox says "unknown user". All other mail to all other domains are delivered. Also AOL messages coming into the office are delivered promptly. Does anyone know why this is happening? Is this an AOL problem or is it a problem I should be looking at?

18 replies

by bfilmfan

I would say there is a problem on the AOL mail server with those mail accounts, if mail delivery to all other domains is normal.

In regards to the AOL mail accounts, can those accounts send mail to your system from their system?

by fabio

I have exactly the same issue. AOL must've just blocked a number of sites/ip's or something, because as of a month a go I did not have this problem. So far everything points to a blocking domain issue @ AOL. I'm having no problem with any other domains at all which tells me that the problem is not in my Exchange server. Did you get the issue resolve, if so how?

by fabio

By the way my e-mail is fabio@xpni.com. (Previous post)
Thank you!!!

by davidb

We are having the issue. When calling tech support at AOL they tell me it's our Exchange server as they have not blocked anything. How do we resolve this problem if AOL is not willing to help?

Any help is greatly appreciated.

Thanks!!!

by pablo.ormeno

i solve this problem telling to my ISP that add the reverse DNS. now i don't have problem with aol.com

by bchana

I'm receiving this on my mail server. I read the answers. Just a quick question why now. My External DNS is handled by my ISP like someone else posted. My mail server is in the DMZ, do I need to contact my ISP to have them add my mail server's reverse DNS entry. Kinda confused please enlighten.

This discussion is closed to new replies.