Very interesting. I own the domain texasconcretebusters.com. I downloaded Thunderbird (latest version) to use as my email client. I have 2 accounts - info@ and bhallman@. I cannot send from one to the other. I can send to & receive from other domains just fine. The sent boxes contain the emails but they never seem to leave Thunderbird. I deleted both email addresses from the address book and collected addresses and that didn't help. I contacted my host and used their webmail service and it worked just fine. Anyone have any ideas before I uninstall/re-install the application and have to setup all my mailboxes again? Thanks in advance!