Overview: In this guide you will find out why Thunderbird won’t connect to mail server? What are the major causes and how to fix the issue without losing any data.

If your Thunderbird could not connect to mail server, then you are not the only one who is facing this problem. It usually happens when users change their passwords or update the Thunderbird app or the server settings.

Table of Contents Hide
  1. Reasons Behind Thunderbird Mail Server Problem
  2. Best Alternative
  3. Manual Methods to Fix
  4. Disable Antivirus/Firewall
  5. Error After Password Change
  6. Thunderbird Won’t Connect to SMTP Server
  7. Conclusion

Why Thunderbird Could not Connect to Mail Server?

These are the reasons behind Thunderbird won’t connect to mail server problem.

  • It is because your Thunderbird fails to make a secure connection with the incoming or outgoing server
  • When you have done wrong IMAP, POP3, or SMTP configurations
  • Due to an invalid username and password
  • If you are using an outdated version of Thunderbird
  • There can be problems with SSL/TLS settings
  • When your antivirus or firewall is blocking Thunderbird
  • Having some kind of network restrictions
  • Because of corrupt Thunderbird profile or mailboxes
  • Temporary mail server downtime

Identifying the real cause can help you in resolving problems.

Also Read: Thunderbird Notifications Not Working

Common Signs of Thunderbird Mail Server Errors

You may see one or more of the following symptoms:

  • Thunderbird keeps requesting a password
  • You cannot download the messages
  • Cannot send outgoing messages
  • Error message “connection timed out”
  • You may see “connection declined”
  • Cannot reach server notification
  • Authentication failed messages
  • Folder synchronization issues

If you experience all the above problems at once, then it must be a networking or Thunderbird setup issue.

Professional Solution to Restore Thunderbird Email Data

After trying all the possible troubleshooting techniques, it is still showing Thunderbird won’t connect to mail server problem. In many cases, it is because of your damaged profile which can create many problems even if your server settings have been set correctly. This might take up a lot of your time, when you are dealing with multiple accounts or archived mailboxes.

A better way is to use SysTools Thunderbird Import Wizard which helps users to import MBOX, EML, EMLX, & Maildir files into the newly created profile of Thunderbird. It also maintains the folder structure, attachments, format of the messages, and metadata. This method will be very helpful for making the Thunderbird profile when there is an issue related to corrupt profile migration.

How to Fix Thunderbird Won’t Connect to Mail Server Error? Manual Fixes

You can try these 8 methods to resolve Thunderbird mail server problems.

#1. Check your Internet Connection

Verify, if your internet speed is stable before making any changes to your Thunderbird settings. You can try these steps:

  • Firstly, visit web pages on your browser
  • Next, reboot your router
  • Use a different Wi-Fi network
  • For once, turn off your VPN

Thunderbird may fail to connect to the mail server if your internet connection is unstable.

#2. Verify Incoming and Outgoing Server Settings

Incorrect server settings are one of the most frequent sources of error.

Incoming Server

  • IMAP or POP3
  • Server hostname
  • Port number
  • IMAP/POP3 security
  • Login method

Outbound SMTP

  • SMTP server hostname
  • SMTP port
  • SSL/TLS
  • Username

This can fix Thunderbird won’t connect to mail server problem.

#3. Type your Email Password Again

In case you have recently changed the password for your email account, Thunderbird will continue using the old one.

  • Firstly, launch Thunderbird
  • Next, delete the old password
  • Close and relaunch Thunderbird
  • Here, type in the new password

This could also resolve the Thunderbird Could not Connect to Mail Server error.

#4. Disable Antivirus or Firewall

There is security software which can also block encrypted connections by Thunderbird too. You need to enable:

  • Email scanning for viruses
  • Firewall
  • SSL scanning

If Thunderbird starts to work properly, add Thunderbird to exceptions.

#5. Configure SSL/TLS Settings

A conflict between the encryption settings and the server ports causes problems in connecting Thunderbird.

You need to confirm:

  • SSL/TLS is configured if needed
  • STARTTLS is chosen if necessary
  • Used for ports correspond to the security protocol

Wrong configuration often leads to connection timeouts.

#6. Remove & Recreate Email Account

Before you delete your account, just make sure that your emails are backed up. Especially if you are using POP3.

#7. See if the Mail Server is Down

This time, the problem is not with Thunderbird. The mail server of your provider can be:

  • Under maintenance
  • Facing downtime
  • Having some problems with the authentication process

#8. Create a New Thunderbird Profile

If you have a damaged Thunderbird profile, it may not communicate effectively with the mail server. For that:

  • You need to create a new profile to know whether the problem is inside Thunderbird or the email account
  • If the new profile operates normally, then your existing profile must be corrupt

Thunderbird Could Not Connect with Mail Server After Password Change

It is one of the common issues faced by many users when they change their email password. This can be because of:

  • Your previous password is saved in password manager
  • Expired OAuth token
  • Security certificate mismatch
  • Cached authentication tokens

Removing the old passwords will usually resolve the Thunderbird won’t connect to mail server issue.

Thunderbird Cannot Connect to IMAP Server

If only the incoming messages are not working, you must check your IMAP settings first. Check these below factors:

  • IMAP is activated in your email account
  • You are using the correct IMAP server
  • Port number
  • SSL/TLS encryption is active
  • Authentication method

Having large mailboxes may also take more time to synchronize after a connection.

Thunderbird Cannot Connect to SMTP Server

If you are in a situation where you are receiving your emails, but not able to send. Then, the problem lies with the SMTP server.

  • Incorrect SMTP Port
  • Outgoing Authentication Off
  • ISP Blocking SMTP Ports
  • Firewall Intervention

Corrected SMTP settings will solve the issue.

Tips to Prevent:

  • It ensures that Thunderbird is always up-to-date
  • Use the right settings for IMAP and SMTP
  • Make frequent backups of your Thunderbird profile
  • Do not turn off your system in between
  • Check your SSL/TLS settings after you make any changes to your accounts
  • Always change saved passwords immediately after you change them
  • Configure your antivirus correctly

It will help reduce connection problems in the future.

End Note

The Thunderbird won’t connect to mail server error is typically because of corrupted profiles. What you can do is recheck the settings and security configuration to get back to normal. However, if the reason behind your issue is your Thunderbird profile, then you can use our professional solution to make things easier.