Friday, 4 September 2015

Exchange 2013 cross forest mail flow

The below instructions are how to ensure that mail flow works when migrating mailboxes from one forest to another. In this example, emails are going to the domain which has mailboxes in the domain in the forest and the domain which is the root domain of a separate forest.

After a mailbox is moved from the source forest, the mailbox is replaced with a mail enabled user which then redirects the mail to the mailbox in the target forest.

Source Exchange server:
Target Exchange server:

To ensure that mail can be delivered to all mailboxes, no matter which forest they are part of: 

  1. Set up an internal send connector on contasex01 to send email for to litex01
  2. Set up an internal send connector on litex01 to send email for to contasex01
  3. Ensure the receive connectors on both contasex01 and litex01 are configured for anonymous authentication and will accept connections from the other server.
  4. Set up a new accepted domain on litex01 for and ensure it is not authoritative but set to internal relay. Internal relay means that when litex01 receives an email for a address, it'll try to deliver to the recipient in its forest and if it doesn't find a valid recipient, it'll send it through the send connector to contasex01. 

1 comment:

  1. Great, thanks for sharing the script to migrate mailbox from exchange and migrate the entire or selected mailbox data to Exchange Online from your Exchange server. But I tested the automate exchange migrator tool from