Setting up your SMTP server in Thunderbird.

initially, smtp setup is only offered when you set up your first email account.

If you want to add more than one smtp servers. goto acount settings. click "outgoing server(smtp)", then click "add" on the right panel to add a new smtp server.

After set up, if you want to let each of your email account to use different smtp (outgoing) server. You need to click that account, and on the right panel, choose the smtp servers from drop down menu for the corresponding email account.