I recently upgraded from Eudora. I have 5-6 personas. My main persona has hundreds of e-mail addresses mapped to it. (Every time I set up a new account with a vendor or a website, I create a new e-mail address, just as I did for this forum, and in our mail server, I map that new alias e-mail address to my primary e-mail address. I do this to cut down on SPAM, and it works really well.) In Eudora, and initially after I installed Thunderbird, if I received mail to one of my aliases and I replied to that message, the "from" address in the outgoing message would be the alias. In Eudora, I had the option of pasting the alias into the "from" field. In Thunderbird, I don't have that option. Thunderbird just displays the persona and gives me the option of changing the persona. For awhile, even though I couldn't see the e-mail address when I was composing the message, the alias e-mail address would show up in the "from" line. Now, only my primary e-mail address shows up in the "from" line. I wouldn't want a new persona for each e-mail address, or I'd spend all morning entering passwords to pick up mail.