451 4.4.0 DNS query failed

[ryrae]

We recently started internally hosting a website for a purchased company(abc.com). The email for abc.com is hosted by google mail. We have the external(AT&T) DNS configured with the appropriate MX, A, and PTR records and the website is accessible from the outside world. The problem we are having is when we setup the internal DNS for abc.com as a primary zone the email sent from internally is queued up(DNS query failed) and eventually the message is dropped. When we remove the internal DNS messages are sent fine from internal users. It seems like a connector needs to be configured for the exchange 07 hub transport or internal DNS needs to be changed.....? Any help is appreciated.

A+, Network+, MCP

 

[58sniper]

You need to create an MX record in your internal DNS zone for abc.com and point it to the external email host.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[ryrae]

We tried that earlier today, but we will revisit that configuration again to see if we missed anything. If that does not work could there be anything within Exchange that needs to be changed/added? I will let you know. Thanks

 

[58sniper]

If you have an internal lookup zone, abc.com, but the mail is hosted externally (google mail), you MUST have an MX record in the internal zone that points to the external mail host. Something like:

type: A
IP: 123.234.123.234 (IP of external mail host)
name: mail (mail.abc.com)

type: MX
name: mail.abc.com
priority: 10

If you don't have internal records, then Exchange isn't likely going to know where to send mail for abc.com (since you have an internal lookup zone, your DNS server is going to think it's authoritative for the domain, and not forward lookups outside). At that point, Exchange is going to bounce the mail.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[ryrae]

Thanks for the reply. In our internal DNS we currently have two primary zones, our corporate domain(mydomain.org) and the hosted domain(abc.com). We added the A record and the MX record for abc.com but the test emails still queued up and eventually failed so we removed the zone so email could be sent again. We only gave it about 30 minutes and we figured the apporpriate replication would have completed, but do you think we should give it more time? I agree that you solution should work, but I don't know if we are overlooking something else? Do we need an external relay setup on exchange 07 for the external domain? We have tried that by itself(with no success), but maybe we need to have combination of things happening to make this work. Thanks agian for any help you can provide.

 

[ryrae]

Fixed....we took your suggestion and re-created the primary zone and added the MX records for the new domain. we had tried that before but it didn't work. We found that we didn't wait long enough for replication to occur between the DCs, the Exchange boxes and Hub Transport servers. I just did a DNS flush and register on each box then tried to send an email and it worked. thanks again for your help.