I have three separate Yahoo email accounts. I set up Thunderbird to link to each Yahoo email account separately. It worked fine for a year or more. On 5/25/26 one of the three Thunderbird email accounts stopped downloading emails from Yahoo. I could see at the bottom bar Thunderbird indicating that is was downloading 1 of XX emails, but never actually downloads them. There is no error message. I checked the Yahoo email account to verify the number of emails I am missing from Thunderbird and the number is correct. I can see the emails in Yahoo. I'm the only person using Thunderbird, so no changes have been made to previous settings for retrieval. I confirmed Security and server settings for Thunderbird in and out going emails, and Yahoo are correct. I tested the connection in Thunderbird, and the connection is successful. I tried to send an email from the Thunderbird account having issues, and the email was sent and received by the recipient. The recipient replied, and Yahoo received the email, but failed to download it to Thunderbird...along with all the other emails since 5/25/26. I unlinked the account and reestablished the link between Yahoo and Thunderbird, and still not fixed. I tried restarting the computer, with no change. I tried to send an email from Thunderbird to one of the other Thunderbird emails and it was sent and received. I made changes to Thunderbird to force the download of emails, and it still wouldn't do it. I turned off my antivirus, closed Thunderbird, and restarted it, and that didn't change anything. The capacity of emails on the email in question only has 739 emails, so it's not over the limit and I have plenty of storage capacity. Thunderbird is set to save emails, Cookies and cache were cleared, no change. I ran the folder repair feature in Thunderbird, but there was no change. I compared all the settings between the other Thunderbird emails that are working against the one that isn't, and they are all the same. There was a suggestion to close out of Thunderbird and delete the "Global-message-db.sqite" file from the Thunderbird profile in case it was corrupted, and it would recreate this file when Thunderbird was restarted. The file was recreated, but it didn't fix the problem. There was mention that a suspicious email in Yahoo might be blocked by Thunderbird, so I placed various emails in the spam folder, and it didn't work. I did find one email in the Yahoo spam folder that was dated before 5/25/26 and moved it to the Yahoo inbox. Lo and behold, that one email downloaded to Thunderbird. So there is something within Thunderbird preventing emails from downloading after 5/25/26. I've read many people complain about similar download failures with no solid fix. Someone mentioned it fixed itself on a day, but then stopped again days later. Someone else mentioned Yahoo changed its password protocol to transfer emails, but that doesn't make sense since the other two are still downloading based on the "old" password protocol. I'm at wits' end. Thanks for reading all of this. I hope someone has a solution.