Gmail POP3现在需要应用密码

[JammyDodger]

您的听起来更像是最近的更改，该更改现在强制您为您的 Google 帐户使用 2FA 和应用程序密码：

Connection to the POP3 server is failing with an authentication error. Please check your POP3 settings

I recommend turning on 2FA on the account and setting up an App Password for Discourse. The policy change is about the “allow less secure app access” option being deprecated. More info on this here: