R2_D2
asked on
Exchange 2010 - 451 4.4.0 DNS query failed
Hi Guys,
We just started using mimecast for spam filtering, inbound emails works fine but problem is with the outbound emails.
Basically email should be routed through the mimecast servers but when use the mimecast's server FQDN on the send connector the email gets stuck in the queue with the 451 4.4.0 DNS query failed error ( see attached ).
I thought it was DNS issue with the exchange server and for that reason I ran a nslookup but it resolved the names properly, then I tried with telnet and I was able to connect and even to sent emails through the eu-smtp-outbound-1.mimecas
This is not a firewall issue because I am able to run telnet tests.
I have been working on this for the past 2 days but still unable to figure it out :(
Queue.jpg
We just started using mimecast for spam filtering, inbound emails works fine but problem is with the outbound emails.
Basically email should be routed through the mimecast servers but when use the mimecast's server FQDN on the send connector the email gets stuck in the queue with the 451 4.4.0 DNS query failed error ( see attached ).
I thought it was DNS issue with the exchange server and for that reason I ran a nslookup but it resolved the names properly, then I tried with telnet and I was able to connect and even to sent emails through the eu-smtp-outbound-1.mimecas
This is not a firewall issue because I am able to run telnet tests.
I have been working on this for the past 2 days but still unable to figure it out :(
Queue.jpg
DrDave242
Did you follow the procedure shown here for setting up the SMTP connector?
Check whether you have external DNS servers listed on the Receive Connector. That can sometimes cause this problem.
Also be aware of this issue with DNS:
http://support.microsoft.com/kb/2508835
That can be caused by some firewalls.
Simon.
Also be aware of this issue with DNS:
http://support.microsoft.com/kb/2508835
That can be caused by some firewalls.
Simon.
ASKER
DrDave242, I did follow the instrucitons from the link but didnt help.
Simon, my exchange server is win2012 and the patch was incompatible.
Also my default received connector had some IP addresses on the " receive mail from remote servers that have these ip addresses " and i just removed them and left the default settings " 0.0.0.0-255.255.255.255" and "::ffff.ffff.ffff.ffff "but unfortunately it did't fix it :(
this issue is very weird.
Simon, my exchange server is win2012 and the patch was incompatible.
Also my default received connector had some IP addresses on the " receive mail from remote servers that have these ip addresses " and i just removed them and left the default settings " 0.0.0.0-255.255.255.255" and "::ffff.ffff.ffff.ffff "but unfortunately it did't fix it :(
this issue is very weird.
ASKER CERTIFIED SOLUTION
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ASKER
tried with the "Use the External DNS Lookup settings ont the transport server" but didn't work neither.
How can i specify dns servers explicitely ??
Finaly, I didn't edit the host file because the eu-smtp-outbound-1.mimecas
How can i specify dns servers explicitely ??
Finaly, I didn't edit the host file because the eu-smtp-outbound-1.mimecas
through the properties of the "external dns servers"
you can associate as many ip addresses you want with a single name in a host file by adding multiple lines. this is only a poor man's workaround
can you confirm that running nslookup on the exchange server gives the proper address ?
you can associate as many ip addresses you want with a single name in a host file by adding multiple lines. this is only a poor man's workaround
can you confirm that running nslookup on the exchange server gives the proper address ?
ASKER
Sorry for the late reply.
The Setting "Use the External DNS Lookup settings on the transport server" and restarting the exchange server fixed the problem.
Thank you for your help.
The Setting "Use the External DNS Lookup settings on the transport server" and restarting the exchange server fixed the problem.
Thank you for your help.
good to know this required a restart. thanks for sharing
best regards
best regards