With Gmail, each account needs to have its own specific gmail smtp setting. So if you have three different Gmail accounts on an installation of Thunderbird, you need three different and corresponding Gmail settings under Tools|Account Settings|Outgoing Server (SMTP). It seems to me that ''darren@gmail.com'' is using the SMTP for ''third@gmail.com''. Even if you choose the darren account, and the message says it's from "Darren", Googlemail will silently replace the "from" address in your message with the name and address of the SMTP that was used, which would appear to be the one for third@gmail.com So, make sure you have all the different SMTP settings. Use the working one (third@gmail.com) as a template; you'll need to change the associated email address to match your incoming addresses, so you'll have three SMTP settings, for test1@gmail.com, darren@gmail.com, third@gmail.com. Then in each account's incoming settings, look under Server Settings where it says which SMTP it uses, and change that to connect it to the appropriate SMTP setting. On the first time of using each of these new SMTP "accounts" you'll be asked for its password. As an aside, I find it is clearer if I avoid reliance onthe word "email" and say instead account, message, address, server, client, etc. ''In work I have Thunderbird set up on 5 different computers. Each computer has 3 different email '''accounts''' attached to their Thunderbird'' ''When an email '''message''' is sent from one computer from the first email '''account''' it is shown in the receiver's email '''client''' as the second email '''address'''.'' Did I understand you correctly?