Using Two Domains in Exchange Server

This question is from an administrator:

I have an Exchange server receiving email for two domains. Users are running Outlook 2010. If someone sends one email to both domains & same user (eg fred@company1.com and fred@company2.com ), then Fred only sees one email in his Inbox. The ‘To’ field does show Fred’s name twice ( resolving each address to his name ), but I would expect 2 separate emails to appear in the Inbox, one to each address. How can I make Exchange or Outlook show separate emails?

When one message is sent to two addresses assigned to the same mailbox, this behavior is normal. While you can have multiple SMTP addresses for a mailbox, Exchange (and many SMTP servers) won’t deliver multiple copies to the mailbox as there is only one email account.

Furthermore, replies will be sent from the default SMTP address, not the individual address it was sent to.

If the message is sent twice (separate mailings), one to each address, there will be two copies.

Workaround #1

One option is to create a distribution list in the GAL for each secondary address (remove the addresses from the mailbox first) then make the mailbox the only member of the DL. Messages sent to the address will go to the DL for distribution to the members, which in this case, is just one person. If the mailbox has Send as rights on the DL, the user can reply from these secondary addresses too.

I recommend using Fred (Company 2) as the display name on the DL so addresses are easier to identify.

One drawback to this method is if there are a lot of addresses or a lot of users, it makes a lot of DLs in the GAL.

Workaround #2

A second option, which is very workable since you use Outlook 2010, is a separate mailbox for each company. Outlook 2010 allows you to add multiple Exchange accounts to the profile.

Pros: It’s easier for users to reply from the correct address. Email sent to each company is segregated in separate mailboxes.

Cons: If the users use smartphones or OWA, they need to set up each account on the smartphone or log into each account separately using OWA.