Mozilla Thunderbird is an email service that boasts excellent privacy features, multi-account support, reliable spam filters, and many customization options.
But even a reliable email service such as Thunderbird may stop working from time to time. In this guide, we’ll show you what you can do if Thunderbird fails to send or receive emails.
Cannot Send or Receive Emails on Thunderbird
Check Your SMTP Server Settings
Use this method if you can’t send emails.
The SMTP server (Simple Mail Transfer Protocol) plays the role of the mailman in the email world. In other words, the emails you send are first collected by the SMTP server. The server then distributes them to the recipients.
Not using the correct SMTP settings may prevent you from sending emails using Thunderbird. That’s why you need to make sure you’re using the correct SMTP server settings.
Ensure you’re not trying to send emails from Thunderbird using the SMTP server of another email service.
- Launch Thunderbird and click on the menu.
- Then go to Account Settings.
- Select your account name.
- Click on Outgoing Server.
- Check the SMTP server settings for your email address.
If you don’t know what SMTP settings to use, check Thunderbird’s support pages:
Check Your IMAP Server Settings
Use this method if you can’t send emails.
- Click on the three-lines to open the menu.
- Then navigate to Options.
- Select Server settings and make sure you’re using the correct IMAP Server settings.
For more information on the IMAP settings to use, go to the official webpage of your email account provider.
Whitelist Thunderbird or Disable Your Antivirus/Firewall
Your antivirus or firewall might be preventing Thunderbird from delivering your messages. Or they could be blocking the emails coming to your inbox.
To test if your antivirus or firewall is blocking outgoing emails, simply disable the tools. If you can send and receive emails with the antivirus and firewall off, whitelist Thunderbird.
If you’re using Windows Security:
- Navigate to Settings → Update & Security → Windows Security.
- Then click on Virus & threat protection → Manage settings.
- Select Add or remove exclusions → Add an exclusion, and select Thunderbird.
If you’re using Windows Firewall:
- Type ‘firewall‘ in the Windows search box.
- Then click on Allow an app through firewall.
- Click on the Change settings button.
- Hit the Allow another app button and add Thunderbird to the list.
The steps to follow are different depending on the antivirus/firewall you’re using. For detailed instructions, go to your antivirus/firewall official support page.
If this problem occurred shortly after you updated Thunderbird, whitelisting the email tool should fix it. Your antivirus/firewall may not trust the new Thunderbird version.
That’s why you need to get your security programs to recognize and trust the updated Thunderbird version.
Disable SSL filtering in ESET
If you’re using a security tool from ESET, try turning off SSL filtering. Use this method if you can’t receive emails on Thunderbird.
- Launch your ESET program and press F5.
- This will open the Advanced setup.
- Click on Web and email (or type ‘tls‘ in the search bar).
- Then expand SSL/TLS.
- Use the slider to disable SSL/TLS protocol filtering.
- Save the changes and restart your computer.
Thunderbird 78 and higher require enhanced TLS security standards. The problem is that you won’t be able to send or receive emails if your provider does not support the latest TLS network encryption protocols.
As a workaround, you can rollback Thunderbird. You can find the list of previous Thunderbird versions on Mozilla’s support page.
Contact Your ISP
Some Internet Service Providers tend to block outgoing emails on certain ports (port 25). Switch to another port or contact your ISP for further help if you still can’t send emails.
If you have problems receiving emails, check if everything is up and running on your ISP’s end. Contact your ISP and check if they set up a spam filter. Such a filter could block or even delete the emails addressed to you preventing them from landing in your inbox.
This post was written by Madalina Dinita and was first posted to Technipages
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