I can receive, but can't send emails. I tried the solutions mentioned on the help page, but no change.
Wšykne wótegrona (3)
Who is your email service provider and what type of account is it (IMAP or POP)?
ISP is shaw.ca | email program is Thunderbird | IMAP
The settings in Tools/Account Settings, Outgoing Server (SMTP) at the bottom of the left pane, should be:
mail.shaw.ca on port 587, STARTTLS security, authentication = normal password, User Name = part of address before @.
Incoming in Server Settings: imap.shaw.ca on port 993, SSL/TLS, authentication = normal password, User Name = part of address before @.