How to fix Mozilla Thunderbird cannot send messages?
Verify your SMTP outgoing email settings In the Thunderbird menu bar, click the Tools menu and select Account Settings , or click the Application menu button and select Options and Account Settings from the sub-menu, and select Outgoing Server (SMTP) from the bottom of the list in the left panel. Check that the settings are the same as documented on the mail settings article for your mail provider. Check that your Thunderbird settings match the documented settings. Verify the correct SMTP Server is being used In the Thunderbird menu bar, click the Tools menu and select Account Settings , or click the Application menu button and select Options and Account Settings from the sub-menu, and select the account name. Verify that you are using the right SMTP server for the email address. Most of the time you cannot send messages from one account provider using another account provider's service. For example, you cannot send a mail from "joe@gmail.com" throug