How to send message to private mail server

Question

Hi,

We have VPN to setup between our environment to 192.168.5.132.

From internal Exchange server (2016 Std) we can talk to this address 192.168.5.132 on port 25

From exchange online we can’t talk to 192.168.5.132 as its only available from On-prem not exchange online. VPN is only setup on-prem servers not exchange online.

 

We have a contact in AD with address as “abc@192.168.5.132” then this address is added onto an distribution group e.g. dl@xyz.co.uk

When email is send to “dl@xyz.co.uk” it forwards the email to “abc@192.168.5.132”

 

We have mail flow send connector, if any email are send to abc@192.168.5.132 it should be routed from exchange 2016 box but for some reason they try to go from exchange online not from our exchange 2016 box.

 

If we send email from yahoo or gmail or exchange 2016 to “dl@ayz.co.uk” we do received them in “abc@192.168.5.132” but when we send email from Exchange online mailbox it fails with below error

 

Reason: [{LED=550 5.4.315 Message expired, connection timed out};{MSG=Socket error code 10060};{FQDN=192.168.5.132};{IP=192.168.5.132};{LRT=10/20/2023 6:10:15 AM}]. OutboundProxyTargetIP: 192.168.5.132.

Any email send to abc@192.168.5.132 should only go though our exchange 2016 box not exchange online.

 

I’m not sure why exchange online is try to send this message as we have mail flow to tell exchange online to let the exchange 2016 box deal with these massage. This was working fine until we change our exchange Cert

 

Thank you

Answer 1

Glad to see that your issue had already been resolved and thanks for sharing the solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept" the answer.

 

 

 

[How to send message to private mail server]

 

Issue Symptom:

We have mail flow send connector, if any email are send to abc@192.168.5.132 it should be routed from exchange 2016 box but for some reason they try to go from exchange online not from our exchange 2016 box.

 

Solution:

In Exchange Online Under Outbound Connector

Under Use of Connector I have add the IP 192.168.5.132 and it start all working