Thunderbird Sending of the Message Failed

If extensions or customized settings are causing the problem, Thunderbird's Troubleshoot Mode can help identify the issue.

• Open Thunderbird.
• Click the Menu button.
• Select Help.
• Choose Troubleshoot Mode.
• Restart Thunderbird when prompted.
• Try sending an email again.

If sending works in Troubleshoot Mode, an extension, theme, or customized setting may be contributing to the problem.

What If Thunderbird Still Cannot Send Emails?

If the above methods do not resolve the problem, the issue may be related to the Thunderbird profile or locally stored mailbox data. This can become more difficult when the profile contains a large amount of email data or when you are already experiencing problems with the Thunderbird application.

In such situations, first create a backup of your Thunderbird mailbox data before making major changes to the profile.

Expert Way to Manage Thunderbird Mailbox Data

If the sending problem is accompanied by profile-related issues, corrupted local data, migration requirements, or difficulty accessing mailbox files through Thunderbird, SysTools Thunderbird Import Wizard can be considered as a professional way to manage and import Thunderbird-compatible mailbox data.

It can import MBOX to Thunderbird without requiring users to manually perform the complete import process through Thunderbird.

Key Features:

• Allows users to import MBOX files into Thunderbird profiles.
• Supports importing mailbox data without depending on the regular Thunderbird import process.
• Maintains the existing folder hierarchy during the import.
• Supports attachments and other email data.
• Provides options to select specific mailbox files or folders.
• Supports bulk importing of multiple MBOX files.
• Can be useful when users are facing difficulties with the Thunderbird application while managing local mailbox data.

This approach does not directly repair an SMTP or email-provider issue. Instead, it provides an alternative way to manage and import local mailbox data when the Thunderbird profile or application is creating difficulties.