Delayed sending email

Frequent Contributor



We have two on-premise Exchange 2016 servers which are configured as hybrid environment with Office 365. We have a claud application which uses the on-premise Exchange to relay emails. It was working fine until recent, the email delivery has been delayed for a few hours. I have reached out to Office 365 support and they pointed out the delay is happened at the place where Exchange relays email to Office 365.


How to troubleshoot the issue? If I don't use Exchange server to reply the email, instead I use the Office 365 SMTP server directly, does the POP and IMAP need to be enabled for the email account? Please help!


Any advice will be highly appreciated!


Thanks in advance!

3 Replies

@Grace Yin Have you checked your Connector logs on why the delay is happening, Check Event viewer on your Exchange servers to see the possible error code, also check Get-queue on why the emails are delayed along with number of Shadow Copies in Shadow Queue.

Re-Run HCW to correct everything on priority.


Cheers !

Ankit Shukla


Hi Ankit,


Thank you very much for your reply. Can you tell me which connector log should I check? 


I checked Event Viewer and found one error which seems related. See the image below.




The source IP address is the application server IP. The email relay has been working fine for a long time. I don't think there is any change on the application server. Don't know why the issue suddenly happens. 


Please advise!

Thanks in advance!

@ankit shukla 

@Grace Yin  i dont think the IP is added in the Relay of your Receive Connectors.



Go to your Exchange Admin Center (On-Premise) & Follow this Path - Mail Flow < Receive Connector , open front end - and see if the IP Address is added for your Web Server or not.


You may also verify in send connector for relay, if the IP is added or not. if it is not please add and then from Elevated CMD (On Exchange Server itself) - IISRESET FOR refresh in Web Services.


Test and see if it works :) 


Cheers !

Ankit Shukla