email lost upon send command

[dorjharrell@cox.net]

I currently have 2 email accounts, both of which have been working just fine until one day last week when I composed a new email in the first account...I saved a draft, but when I clicked SEND both it and the draft disappeared...Tried the same message from the second account (adding account one as a cc address) and it went out as usual and was received successfully on the first account...after much trouble shooting, I ascertained that the second account is fully functional...All functions on the first account appear normal except for the aforementioned SEND... I verified that settings for both accounts are identical except username and password...I even removed and re-installed the entire program from a fresh download....Is there something I may have inadvertently done (possibly security or authentication related) that is preventing the sending of a message??