10.6 Mail Server Sending mail using FQDN

I have configured a 10.6 mail server and am in the process of testing. All seems to be working well, but when I send mail it is sent as from the FQDN not the Mail Domain. Mail can be sent to the Mail Domain and it is delivered to the correct user. I have unchecked the check box that says use local domain, have added the appropriate domains, Like I said, can send and receive mail form the account, just mail being sent had the FQDN as the return address (it works but I don’t want it visible).

Example: User@mail.domain.org is sent as from user@FQDN.Too.long.org

Any suggestions would be greatly appreciated. Was supposed to roll this out over christmas break, LOL, OH well another Tech project behind schedule!