SQL Database Mail Error The mail could not be sent to the recipients because of the mail server failure. Exception Message: Cannot send mails to mail server. (Service not available, closing transmission channel. The server response was: 4.3.2 Service not available).

In a client's set up, there is a database mail server that sends mail externally via an Exchange server. Great, no issues with that... Until I wanted to set the test environment to also send test mails... For some reason I would get the following error:

• The mail could not be sent to the recipients because of the mail server failure. (Sending Mail using Account 4 (2015-12-05T17:18:36). Exception Message: Cannot send mails to mail server. (Service not available, closing transmission channel. The server response was: 4.3.2 Service not available).

I double-checked my config's, but no joy. So I went delving into Exchange (this is a Windows 2011 SBS Standard box)...


I took a step back, and asked myself what am I trying to do... I am trying to use Exchange to relay messages to the internet... RELAY, of course!!! SMTP Relay connectors!!!


Quick as a flash,

• I went to Microsoft Exchange -> Exchange On Premise -> Server Config -> Hub Transport
• I double clicked the SMTP Relay connector
• Clicked on Network
• Added the IP address of the test server to "Receive mail from remote servers"
• OK
• Ran the test again

TA-DA!!! It works


Hopefully this will save anyone out in CyberLand countless hours of testing :)


Enjoy


Z