Hi,
I am working on a Issue on a Exchange 2016 Environment (15.1.1713.5)
We have a DAG of 3 Servers lets say ServerA, ServerB & ServerC
2 of them (ServerA & ServerB) are on Site A (Primary/Production Site). There are 2 DCs in this site
3rd Server (Server C) is on Site B (DR Site). There is 1 DC in this site
There are multiple Databases (about 20+) which were actively mounted on Server A but due to this issue, we have them Actively mounted on ServerB (While functioning fine on Server B with no users complaints) whereas on rest other Servers they are offcourse passive
The reason we moved all the DBs to ServerB is because none of the emails could deliver while the DBs were active on ServerA as all emails were seen in Queue
Next Hope Domain: testdb1 (Name of Mailbox Database)
Delivery Type: SMTP Delivery to Mailbox
Status: Retry
Last Error: [{LED=451 4.4.397 Error communicating with target host. -> 421 4.2.1 Unable to connect -> SocketConnectionRefused: Socket error code 10061};{MSG=};{FQDN=testdb1};{IP=ServerA IP})
All the Databases (DAG database activation preference) is set on ServerB since it is working fine
To reproduce the issue, I have manually activated the database 'testdb1' on ServerA & we have just 1 mailbox residing in this DB. If i try to send email from the mailbox to self, the email remains in draft (OWA) & can be seen in queue on server with below error message
Steps Tried for resolving the issue
Changed the DNS Servers - Have them same as what is configured on ServerB which is working fine on ServerB
Doesnt seems to be DNS issue
Restarted the Transport Service
Reboot the Server
Recreated the Queue Database & rebooted server
When the DB moves automatically to ServerB (as per DAG activation preference), the emails which were in the queue are instantly delivered
Similarly if we activate the mailbox on ServerC, that works fine as well. i.e ServerB & ServerC works fine but this issue is only on ServerA
Apart from the queue 'SMTP Delivery to Mailbox' There is no other queue observed which should be filled with messages.
Pl suggest how can we resolve this issue.