Thunderbird Outgoing Server Settings: Complete SMTP Configuration Guide

Authentication requirements depend on the account and Google’s existing security policies. If Thunderbird presents a Google Authentication window, and sign in.

Outlook and Microsoft 365 Thunderbird SMTP Settings

The SMTP server for Microsoft email services varies according to the service and account environment.

• Use smtp.office365.com for Microsoft 365 accounts
• You can go for port 587 with STARTTLS for secure outgoing email
• Ensure that you have enabled SMTP Authentication for the account
• Your organization’s Microsoft 365 admin may block SMTP AUTH

Tip: If sending fails again, review your Microsoft 365 account and SMTP settings.

Yahoo Thunderbird Outgoing Mail Settings

Yahoo gives SMTP access and allows you to set it up for email clients like Thunderbird. You will see the following details which you need to fill in.

• SMTP Server: smtp.mail.yahoo.com
• Port: 465 or 587
• SSL: Required
• Authentication: Required
• Username: Full Yahoo email address

Note: Do not change authentication settings without first checking the provider’s latest documentation.

Users can also go for SysTools Thunderbird Converter, if they want to convert their MBOX files into popular formats such as PST, EML, PDF, & more.

How to Fix Thunderbird Outgoing Server Settings? 7 Manual Steps

If Thunderbird can receive email but cannot send it. The issue often comes from SMTP configuration, authentication. Perform the following manual checks in sequence:

#1. Verify the SMTP Server Name

• Navigate to Account Settings > Outgoing Server (SMTP) > Edit
• Validate that the SMTP hostname is one used by your email provider
• Check if you have not made any spelling mistake or missing any character in the server name
• Don’t use SMTP credentials from other email providers or accounts
• If the server address has recently been changed, update it with the latest from the provider
• Hit on save settings and then try to send an email again

#2. Check the SMTP Port

• Open Account Settings > Outgoing Server (SMTP) > Edit to check the set port.
• There are some common SMTP ports 587 and 465 depending on the provider
• Verify the SMTP port as per your provider’s documentation
• Just ensure you do not change the port, else change it based on the security protocol
• Thunderbird cannot connect SMTP server, if the port is blocked or no correct port
• Save the settings and test out the outgoing email after changing the port

#3. Match Security with the Port

• Firstly, check the connection security setting with the SMTP port you have given
• Port 587 is commonly used with STARTTLS for secure mail submission
• While port 465 is often associated with SSL/TLS connections
• If chosen improperly in some other way, you will face data connection errors
• Always use your email service provider combination of security
• Restart or re-connect thunderbird after editing the security settings

#4. Verify Authentication Status

Using this method, you can fix Thunderbird Outgoing server settings error.

• Check SMTP server settings and the selected Authentication method
• Select the supported authentication from your email service
• If you use the wrong method, then it can stop you from successful login
• Current providers might need OAuth2 or another secure way to authenticate
• Verify whether your organization or provider has limited SMTP access
• Now, save the configuration and allow Thunderbird to move ahead

#5. Check the Username

• Confirm the username specified in SMTP name
• Most providers need the full address as the SMTP username.
• Check the username does not have typo errors or unwanted spaces
• Don’t just assume that the part of your text before @ is all that’s needed
• If you are using SMTP, then set the correct username for the SMTP password based on your new email address
• Make these changes and send another test message

#6. Confirm the SMTP Server is Connected to your Account

• Head to account Settings, and select the problematic email account
• Find the Outgoing Server (SMTP) option inside that
• Select a proper SMTP server configuration from the setting
• This is especially useful when you have multiple email accounts configured in Thunderbird.
• If you select another account as the SMTP server, it may lead to authentication or sending errors
• You can also save the correct assignment and send a test email

#7. Re-enter Authentication Details

• Firstly, check your email password, in case it was changed recently
• It is possible that Thunderbird will use your previous credential
• Next, remove the old saved credentials
• Now, allow Thunderbird to request the current password
• If your provider uses OAuth2, then complete the official sign-in process
• Do not follow the outdated authentication methods that is not supported by your email provider

Import Old Email Data into Thunderbird Professionally

There may also be a need to migrate some old mails, for that you can use SysTools Thunderbird Import Wizard. Without doing it manually. It allows you to import MBOX, EML, EMLX and MailDir files directly into Thunderbird which simplifies the email migration.

End Note

The most important thing for sending mail is to fix Thunderbird outgoing server settings. For that, users need to validate their SMTP server name, port, connection security, authentication method and username. It is a very key factor that SMTP server is linked to the respective Thunderbird account is essential. And in case you want to import old email data into Thunderbird, SMTP setup is not the answer. For that, you can take the help of our professional solution.