Monday, May 21, 2012

Forwarded External Emails Don’t Display Sender’s Address

After migrating thousands of mailboxes from Exchange 2007 to 2010, only recently came to my attention a bug in the whole process.

Let’s say we have a user (call it UserA) that has a rule to automatically forward every e-mail received to his assistant (UserB):

Using the scenario above, with Exchange 2007 when an external e-mail is received by UserA and forwarded automatically by the Outlook rule to UserB, this will receive the e-mail like this:

Note that the e-mail address of the external recipient is displayed.

However, with Exchange 2010 the same thing doesn’t seem to happen!... Running the exact same test with both users now on Exchange 2010, UserB receives the e-mail like:

Note that my external e-mail address is not displayed so UserB has no way of replying to the sender!

There are two main workarounds for this:

1. Update the Outlook rule to use one of the following actions instead: “forward it to people or distribution list as an attachment” or “redirect it to people or distribution list”:

However (1) the e-mail will be received as an attachment which means it is an extra step for UserB to read the e-mail and (2) the e-mail will be received by UserB as having been sent directly from the external sender to him/her, when it was actually sent to UserA...

2. At the Exchange level, enable the auto forward feature from UserA to UserB (make sure “Deliver message to both forwarding address and mailbox” is also selected so that both UserA and UserB receive the e-mail):

However this only allows you to specify one user and although the e-mail received has the sender’s e-mail address, it looks different:
For me, this is the best workaround for overcome this issue, but I guess it’s all up to the user how he/she prefers it.

You could specify a second user by using the Shell instead and a little "cheat":
Set-Mailbox UserA -ForwardingAddress -DeliverToMailboxAndForward $true

Reason for This?!
It turns out this only happens for mailboxes migrated from Exchange 2007 to 2010. If a mailbox is created on 2010, it works as expected with the sender’s e-mail address being displayed!

According to Microsoft, this issue was recorded as a bug and was closed as “Won't Fix”, so I don’t expect it to get fixed any time soon...

It is hard to believe that with so many costumers and millions of mailboxes migrated from Exchange 2007 to 2010 all over the world, Microsoft is not planning to fix this, so I am still trying to find out if this is actually the case.

At the time of this post, I am running Exchange 2010 SP2 RU2.


  1. Hey, note that for a cross-forest migration it's worse. In that case, *if* the rules are copied, they are likely broken because the 'send to' part of the rule is a Address Book Identifier (not an SMTP address).

    Priasoft however handles this during migration by modifying the rule in the target mailbox and changes the 'send to' to one-off smtp addresses.

    Problem solved!

    -Eriq VanBibber

  2. Hi Eriq, thank you for letting me know! Never thought about that but it makes sense... It’s a shame these “things” haven’t been fully addressed yet.
    Thanks for sharing!

  3. It's confirmed... There will be no changes to the code causing this issue. It was raised as a Critical Design Change Request and some Risk Assessment was conducted to the code changes needed. However, it became apparent that Out of Office would be made unstable if this area of code was updated... This is why the Change Request was rejected.

    Something to keep in mind in future migrations!...