Steps to Fix Unable Send Email Messages in Thunderbird :
If you are unable to send email messages from your Thunderbird account, there can be two reasons behind this:
- Inappropriate Thunderbird Settings
- Blocked Port 25 by ISP (Internet Service Provider)
Solution – To resolve this error in Mozilla Thunderbird, perform the following:
Step 1: Ensure that Thunderbird settings are appropriately configured:
- Incoming mail server (POP3/IMAP server): mail.yourdomain.com
- Outgoing mail server (SMTP server): mail.yourdomain.com
- Username: the full e-mail address like [email protected]
- SMTP authentication must be enabled for the login to be successful.
Step 2: Try using alternative TCP port 2525 for SMTP Server.