Hi All,
Firstly, I am not very familiar with MS Exchange and am currently on a very steep learning curve!
I've inherited a network which has a Small Business Server 2011 running Exchange 2010, and everything was running fine until it stopped receiving e-mails suddenly.
A blown modem, and replacement later, incoming mail was resolved through some Domain name MX record tweaks, and some tweaking on a WatchGuard XTM 220 firewall.
But I've since discovered that outgoing mail is going no-where - seemingly to any domain.
Having researched this problem, I've attempted a number of the suggested fixes but still the mail sits in the out-queue refusing to budge with the same error message.
This is a single server instance, managing internal mail and a single domain name's mail. (There are three MX records for the domain, to deal with failover ADSL lines).
The WatchGuard firewall is the primary DNS Server for the SBS Server (which I think seems weird given that the SBS server is running a DNS Server too, but it's all been working up to now fine...)
- Disabling IPv6 caused more trouble than it was worth
- The SBS machine is able to NSLOOKUP the domains stuck in the queue, and fetch the appropriate MX records
- The SBS machine is able to telnet to any of the MX record IP Addresses on Port 25
- Checking the 'Use External DNS' option on the Send Connector (with transport restart) doesn't solve anything
- Adding DNS servers of the ADSL modems (static IP - External DNS Lookups - with transport restart) doesn't solve anything
- Clearing the DNS server cache on the SBS machine doesn't fix anything
About the only thing I haven't done, but will do once the users have gone, is reboot the firewall to see if there's an issue there.
(The firewall does have Port 53 and Port 25 opened for the SBS server by the way I checked that!)
Checking the Connectivity logs just shows:
2014-01-03T15:38:05.705Z,08D0D6AD158ECDB4,SMTP,blueyonder.co.uk,-,Messages: 0 Bytes: 0 (The DNS query for 'DnsConnectorDelivery':'blueyonder.co.uk':'d536df7a-8b3e-406b-a877-8bc29803df22' failed with error : ErrorRetry)
Can anyone shed any light on where I should go from here please!?