Force "reply" address to be Alias

[dsirrine]

I am having an issue where we would like to have the e-mail to/from/replyto addresses in the email header to always be the Alias. Currently, our system is set up where the "account name" is the FirstinitialLastname@foo.com. The Alias is Firstname.Lastname@foo.com. We would like to always send and recieve as the alias. However, we have had a few sporatic cases where individuals will send calendar requests to individuals outside the company, and when a reply is sent, it's sent using the account name and not the alias. This seems to be the only condition in which this happens. Any ideas on how to force it to use the alias? Or, if you know what might be causing the problem in the first place?