Hello all, Running Exchange 2003 Pre SP1... I have several users that have (for years) had an apostrophe in their primary SMTP address, and they have had no problems. An Example would be Chris.D'Wall@xxxxxxxxxxxxxxxxxxxx Notice the ' in the example. All of a sudden, 5 days ago, all users with apostrophes in their SMTP address have been unable to send external or receive external e-mails. To fix the issue I have had to set their primary SMTP address to not include the Apostrophe. Using the example above, the new primary would be Chris.DWall@xxxxxxxxxxxxxxxxxxxx This would allow mail to flow from and to the users. Now the weird part - if I leave the Chris.D'Wall@xxxxxxxxxxxxxxxxxxx address as an alias - external senders can now deliver mail to either address. Any ideas on this one? Thanks Chris