Need to connect Thrid party Mail server to Office 365

Dear AdminBMR_244

Good day!

Thank you for posting in Microsoft Community. We are happy to help!

Per your description, I understand you would like for Teams meetings created to be sent to your hosting server (abc.com) ? Do correct me if I misunderstood. To better help assist, please share some information with me:

• Where are the connectors created?

• What Office 365 subscription do you have? I ask this because, If you want meeting invitation sending from abc.onmicrosoft.com to abc.com(hosting server) you need to have an EXO license for abc.onmicrosoft.com accounts, and create a connector between abc.com and abc.onmicrosoft.com, then use mail flow rule to route the invitation email.

• Is any error displayed to show that the connectors are not working? If yes, please share screenshots with us.

For further information on how to connect a third party mail server to Office 365, please see Set up connectors to route mail between Microsoft 365 or Office 365 and your own email servers | Microsoft Learn

Please understand that sometimes our first answer may not solve the problem right away. It depends on what information we get in the thread and the complexity of the question. But through your cooperation, we can find a solution together.

Your patience and understanding is highly appreciated.

Sincerely,

Momo | Microsoft Community Moderator

Thank you for your reply,

1.Connector create on exchange admin >

2.our tenant has M365 Business Std. subscription and already assign to user.

3. This error show when I validate user to connect

Detailed log

Thank you,

Dear AdminBMR_244

Thank you for the response.

Based on your response, since you assigned the users the license and Business standard comes with the Exchange online service.

With reference to the error message shared the SMTP TLS failed, please make sure TLS is enabled for abc.com.

If TLS is already enabled for abc.com I recommend you get in touch with our level 2 engineers as they have more resources to check this from the backend, since you have a business standard subscription, you can raise a free ticket in the Office admin center by navigating to Support>new service request, then type your issue description, and our engineers there will gladly assist.

Your cooperation is highly appreciated. Have a nice day!

Sincerely,

Momo | Microsoft Community Moderator

Hi,Momo

Thank you for your reply,

we edit host an

d re-validate again. then we found this error 550.5.7.1 Relaying to <*** Email address is removed for privacy ***> denied (authentication required)

Where we need to settings? please advise,

Thank you

Dear AdminBMR-244

Good day!

Thank you for the response. Based on the error message received, after searching, I found an article with possible solutions on how to resolve the error message received, please see troubleshooting steps shared in Fix email delivery issues for error code 550 5.7.1 in Exchange Online | Microsoft Learn to see if the error can be resolved.

If after trying the troubleshooting steps in the article the issue persists I recommend you get in touch with our level 2 engineers, as they have more resources to help check and resolve the issue, we can't check this on our end due to limited access so , to solve this quickly it would be best to raise a free support ticket in the Office 365 admin center by navigating to Support>New support ticket.

Your time and understanding is appreciated. Have a lovely day!

Sincerely,

Momo | Microsoft Community Moderator

ok, I try to open ticket in service request.

Thank you for your support