hello
https://wiki.gnome.org/Apps/Geary/FAQ#Using_Google.2BIBk-s_2-Step_authentication
Using Google’s 2-Step authentication
Google's 2-Step authentication is a mechanism to protect your Google accounts by registering access per-computer. Because Geary uses IMAP authentication to access your email, it currently has problems if you have 2-step authentication enabled (see bug #713745).
However, you can configure your account to allow Geary access. Log in to Google with your browser and go to Connected apps & sites. From there, set "Allow less secure apps" to On.
donc cliquer ici
https://myaccount.google.com/security#connectedapps
puis ici
Paramètre "Autoriser les applications moins sécurisées" désactivé
