- Do you mean that mailbox hosted on company A (such as ******@domainA.com)?
- Whether there exists mailbox for this user like ******@domainB.com on company B?
Scenario one: If there doesn't exist ******@domainB.com on company B (which means **the original recipient is ****@domainA.com), just Domain A MX record points to Domain B IP Address. About this one, why not point MX to Domain A Ip address directly?
You can also use the Exchange external relay function to relay emails from company B to company A: Add domain A as external domain on company B, then create send connector to relay emails to domain A.
Scenario two: If there exist ******@domainB.com on company B (Which means **the original recipient is ****@domainB.com). You could take step below to redirect emails from ******@domainB.com to ******@domainA.com
- Add ******@domainA.com as mail contact on company B.
- Create a transport rule on company B like: If the message is sent to '@domainB.com', Redirect the message to '@domainA.com'
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.