connection to server pop.mail.yahoo.com timed out

First thing to do would be to verify your server settings. According to Yahoo's help page (https://help.yahoo.com/kb/SLN4724.html) they should be this: Incoming Server Type: POP3 Incoming Server Name: pop.mail.yahoo.com Port: 995 User Name: <your email address> Connection Security: SSL/TLS Authentication method: OAuth2 SMTP Server Name: smtp.mail.yahoo.com SMTP Port: 465 Connection Security: SSL/TLS Authentication method: OAuth2 User Name: <your email address> Even though Yahoo doesn't mention it, I believe they now require the use of OAuth2 for authentication, and I indicate it above. To force an OAuth2 re-authorize you may need to take some or all these additional steps: - Make sure cookies are allowed (<Settings | Privacy & Security | Web Content | Accept cookies from sites>); - Delete all cookies for that account (<Settings | Privacy & Security | Web Content | Show Cookies>); - Delete all passwords for that account from saved passwords (<Settings | Privacy & Security | Passwords | Saved Passwords>); Now restart Thunderbird. You will be asked for your credentials, an OAuth2 token will be set, and hopefully they will be accepted and mail retrieval will resume. ============ If you have multiple Yahoo accounts set up in Thunderbird, there may be more hoops to jump through. But let's put that off until you try the above.