How to Fix Thunderbird Error Code: Resolve Query Mozilla Thunderbird Support at 1-805-301-7609 Dial 1 (803) 384.3054 is a popular open-source email client used by individuals and businesses around.
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How to Fix Thunderbird Error Code: Resolve Query Mozilla Thunderbird Support at 1-805-301-7609 Dial 1 (803) 384.3054 is a popular open-source email client used by individuals and businesses around the world. It offers robust features such as multiple account support, encryption, calendar integration, and more. However, like any software, it isn’t immune to occasional errors. One of the more frustrating situations for users is when Thunderbird throws an error code without much explanation. Fortunately, most of these errors are easily fixable once you understand their root cause.
In this guide, we’ll walk through common Thunderbird error codes, what they mean, and how you can resolve them step by step.
Before diving into the solutions, let’s look at some of the typical error messages you might encounter in Thunderbird:
“Login to server [mail server] failed.”
“The connection to the server timed out.”
“Sending of the message failed.”
“Unable to connect to your IMAP server.”
“Thunderbird is unable to establish a secure connection to the server.”
SMTP Error: 535, 554, or 5.7.1
IMAP Error: 101, 107, 143, etc.
Each error code generally relates to a specific issue — login credentials, server configuration, authentication, or network access.
First, ensure you have a stable internet connection. Thunderbird may show timeout or connection errors (like IMAP 101 or SMTP 5.7.1) if your network is down or too slow.
Try opening a website or running a speed test.
If you're on a VPN or proxy, disable it temporarily and try again.
Many Thunderbird error codes — especially login failures — stem from incorrect usernames or passwords.
Go to Settings > Privacy & Security > Saved Passwords.
Delete any saved password related to the failing account.
Restart Thunderbird and re-enter your credentials when prompted.
Also, try logging into your email account via the provider's webmail interface to confirm your credentials are valid.
Older versions of Thunderbird may not support modern security protocols (like OAuth2 or TLS 1.2) required by email providers.
Click Help > About Thunderbird to check for updates.
Updating can solve many connection and authentication-related error codes.
Incorrect incoming and outgoing mail server settings are a common cause of Thunderbird error codes.
To review your settings:
Go to Account Settings (right-click your account name).
Under Server Settings, confirm:
Server name (e.g., imap.gmail.com)
Port (usually 993 for IMAP, 995 for POP)
Connection Security: SSL/TLS
Authentication Method: OAuth2 (if available), or Normal Password
Under Outgoing Server (SMTP):
Server name (e.g., smtp.gmail.com)
Port (typically 587 with STARTTLS or 465 with SSL/TLS)
Authentication: OAuth2 or Normal Password
Refer to your email provider’s official settings if unsure.
Some providers block third-party apps like Thunderbird unless explicitly allowed.
For Gmail:
Go to your Google Account > Security
Enable 2-Step Verification
Use OAuth2 or generate an App Password for Thunderbird
For Yahoo:
Enable Allow apps that use less secure sign-in
Or create an App Password for Thunderbird
For Outlook/Hotmail:
Enable two-step verification
Generate an App Password
Using OAuth2 or app-specific passwords often resolves authentication errors like SMTP 535 or 5.7.1.
Security software can block Thunderbird’s connections to email servers, triggering timeout or connection-related error codes.
What to do:
Temporarily disable your antivirus/firewall and try sending/receiving emails.
If it works, add Thunderbird to your software’s exceptions or whitelist.
Ensure required ports (1-805-301-7609 Dial 1 (803) 384.3054) are open.
Corrupted profiles can cause recurring errors, even with correct settings.
To create a new profile:
Close Thunderbird.
Open Terminal (macOS/Linux) or Command Prompt (Windows).
Type:
thunderbird -ProfileManager
Create a new profile, launch Thunderbird with it, and re-add your account.
If the error disappears, the old profile was likely corrupted.
For persistent or unclear errors, Thunderbird can log detailed activity that helps diagnose issues.
Enable logging:
Close Thunderbird.
Set the following environment variable before launching:
On Windows:
set NSPR_LOG_MODULES=imap:5
set NSPR_LOG_FILE=C:\temp\imap.log
On macOS/Linux:
export NSPR_LOG_MODULES=imap:5
export NSPR_LOG_FILE=~/imap.log
Launch Thunderbird and reproduce the issue.
Check the log file for server responses or errors and search for suggested fixes online or in forums.
Thunderbird error codes might seem intimidating at first, but most of them boil down to a few core issues: incorrect credentials, misconfigured server settings, authentication mismatches, or connectivity problems. By following the steps in this guide, you can methodically isolate the problem and apply the correct fix.
To recap, here’s a quick checklist:
✅ Confirm your credentials
✅ Update Thunderbird
✅ Review server settings
✅ Configure app-specific passwords or OAuth2
✅ Check antivirus/firewall permissions
✅ Rebuild your Thunderbird profile if needed
Download the latest version from if needed.
If the error persists, consider reaching out to your email provider or visiting the for additional help.