[Authentificationfailed] [Login invalid credentials]

My IMAP connection to a Yahoo mail account with “k-9 mail” application fails on my Android mobile: \
Incorrect name or password (nom d’utilisateur ou mot de passe incorrect)\
(Command: sensitive; response: #2# [NO, [AUTHENTIFICATIONFAILED], LOGIN Invalid credentials])\

This issue lasts a few months. Today, I set up the same e-mail account on Gmail application instead and it works on my mobile.\
Therefore this issue is due to k-9 mail. \
My login contains special characters. My password is complex (long and many special characters), may it be the reason for this issue ?\
I can not change my mail login. I have changed my mail password twice and still it fails.\
Can someone help me please ?\

Mail services like gmail and yahoo now require either support for OAuth2 or “app passwords” for logging in. “App passwords” are system generated, not what you use for logging in via webmail or the service’s own mail client. With gmail, it’s made up of 4 sets of 4 characters (I believe all lower-case alpha). I suspect that yahoo’s is similar. As K9 doesn’t support OAuth2, you’ll need to use the “app password” approach:



If you are trying to use “complex - long with many special characters” passwords, then you aren’t using system-generated “app passwords”, which is most likely your issue – rather than a problem with K9.

Thank you, njeyaakili.
The tip “app password” is a good one, even if I had tried to skip it.
The long term solution would be that K9 does support OAuth2…

I belive somebody is working on the support for OAuth2.
See Add XOAUTH2 support for gmail and outlook by starshipcoder · Pull Request #4832 · k9mail/k-9 · GitHub

Thank you, poldi171254. They say that they work on OAuth2 support for outlook, and later for gmail. I hope that they won’t forget yahoo.