Mail Settings

POP

Refer to Yahoo!'s help page for POP access settings and instructions for Yahoo Mail.

IMAP

Refer to Yahoo!'s help page for IMAP server settings for Yahoo Mail.

My sign-in attempt was prevented

If you get the Username or password invalid warning and the Sign-in attempt prevented email when you try to connect your Yahoo Mail with Thunderbird, Yahoo has blocked Thunderbird from connecting because it's a "less secure" non-Yahoo app. In Thunderbird below 68.5 you could enable an option to allow apps that use less secure sign-in in your Yahoo Account. See this Yahoo support page for instructions.
Update: please read section 'Important Changes to Authentication Method Notice' below.

In Thunderbird version 68.5 and up you can change the POP server to pop.mail.yahoo.com (port 995).

Important Changes to Authentication Method Notice

If you currently have a POP or IMAP mail account in Thunderbird and receive an email from Yahoo that says:
"We’ve noticed that you’re using non-Yahoo applications (such as third-party email,calendar, or contact applications) that may use a less secure sign-in method. To protect you and your data, Yahoo will no longer support the current sign-in functionality in your application starting on 20 October 2020. "

Check Thunderbird has cookies enabled.
In versions prior to 78*:

1. Select 'Menu app icon' > 'Options/Preferences' > 'Options/Preferences'
2. In 'Options/Preferences' left Pane select Privacy
3. Select checkbox 'Accept cookies from sites'

In versions 78* or later:

1. Select 'Menu app icon' > 'Options/Preferences'
2. In 'Options/Preferences' left Pane select Privacy & Security
3. Select checkbox 'Accept cookies from sites'

Update the 'Authentication Method' for the Pop or Imap mail account.

1. Select 'Menu app icon' > 'Account Settings'
2. Select mail account name in left Pane
3. Bottom right: click on 'Edit SMTP server'
4. Set outgoing server (SMTP) 'Authentication Method' to 'Oauth2'
5. Click on 'OK'
6. Select 'Server Settings' for mail account
7. Set incoming server 'Authentication Method' to 'Oauth2'
8. Click on 'OK'

Exit Thunderbird
Wait a few moments for background process to complete
Start Thunderbird

Then there will be a prompt from your Yahoo ISP partner to login. This is done with a OAuth 2.0 key exchange in Thunderbird which will authenticate the Thunderbird client in future logins.

Import Yahoo!'s Contact List to Thunderbird

1. Open your Yahoo! Mail account.
2. On the right side of the screen (left if you are using the "classic mail"), select the Contacts icon. Your contact list will open.
3. At the top of the list, click the Actions menu.
4. In the menu, select Export....
5. Select Netscape/Thunderbird and click Export Now.
6. Save the yahoo_contacts.ldif file to your desktop or some other place where you can find it later.
7. Open Thunderbird.
8. Under Tools, select Import and then Address Books.
9. Select Text file (LDIF, .tab, .csv, .txt), then click Next.
10. Select the yahoo_contacts.ldif file that you previously saved.
11. Your Yahoo! contacts will be imported as a separate yahoo_contacts address book.

Calendar

To configure the Thunderbird calendar (Lightning) with your Yahoo! Calendar, follow the instructions at the page Sync Yahoo Calendar with Mozilla Lightning on the Yahoo! support site.