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Authentication failure when connecting to server imap.mail.yahoo.com - Yahoo mail

happy_bogan
happy_bogan
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I am getting the popup error message in Thunderbird of "Authentication failure when connecting to server imap.mail.yahoo.com". The issue just started on one of my two Yahoo mail accounts with no change of details (either in Thunderbird or server side). I have verified that ALL settings are the same as the other Yahoo account which is working properly. Apart from the really annoying popup, Thunderbird still seems to function ok, emails send & receive etc.

Current settings in Thunderbird are: User Name: FULL Yahoo email address Server Type: IMAP Mail Server Server Name: imap.mail.yahoo.com Port: 993 Connection security: SSL/TLS Authentication method: OAuth2

Operating System: Windows 7 (Windows 10 on alternate (New) PC)

Things I have tried so far: Changed password several times Enabled and disabled the 'Allow apps that use less secure sign-in' on server side (no difference) Changed 'authentication method' from 'Normal password' to 'Encrypted password' to 'OAuth2' Changed IMAP server to Yahoo's alternate one: imap.mail.att.net (no difference, reverted back to imap.mail.yahoo.com) Installed a new installation of Thunderbird on a different (New) PC - same error message

I love Thunderbird but am at a total loss as to how to resolve this issue, any assistance would be greatly appreciated.

I am getting the popup error message in Thunderbird of "Authentication failure when connecting to server imap.mail.yahoo.com". The issue just started on one of my two Yahoo mail accounts with no change of details (either in Thunderbird or server side). I have verified that ALL settings are the same as the other Yahoo account which is working properly. Apart from the really annoying popup, Thunderbird still seems to function ok, emails send & receive etc. Current settings in Thunderbird are: User Name: FULL Yahoo email address Server Type: IMAP Mail Server Server Name: imap.mail.yahoo.com Port: 993 Connection security: SSL/TLS Authentication method: OAuth2 Operating System: Windows 7 (Windows 10 on alternate (New) PC) Things I have tried so far: Changed password several times Enabled and disabled the 'Allow apps that use less secure sign-in' on server side (no difference) Changed 'authentication method' from 'Normal password' to 'Encrypted password' to 'OAuth2' Changed IMAP server to Yahoo's alternate one: imap.mail.att.net (no difference, reverted back to imap.mail.yahoo.com) Installed a new installation of Thunderbird on a different (New) PC - same error message I love Thunderbird but am at a total loss as to how to resolve this issue, any assistance would be greatly appreciated.

All Replies (4)

Matt
Matt
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If you are accessing the account from two devices, it is possible that the two devices are actually running out of "connections" to the server. Thunderbird usually defaults to 5, so two thunderbird's could be logged in 10 times to yahoo so you get a refusal of more connections.

It might also be worth looking at your calendar settings if you have configured a yahoo calendar.

happy_bogan
happy_bogan Question owner
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Hi Matt, Appreciate the advice, however I only installed the second Thunderbird to the new PC as a 'check' after the initial problem failed to resolve. I only use one device at any given time and have no yahoo calendar. Also makes no difference when trying with addons disabled unfortunately.

Matt
Matt
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Then I would be leaning towards anti virus /Firewall issues. What anti virus are you using?

happy_bogan
happy_bogan Question owner
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Turned off the antivirus & firewall on my main PC, no antivirus installed on the second 'test' PC.