0 votes
by (120 points)

https://support.google.com/mail/?p=BadCredentials ay12-20020a1709028b8c00b001636d95fe59sm10917855plb.172 - gsmtp (535).

Applies to: Rebex Secure Mail

1 Answer

0 votes
by (132k points)
Hello, could you add a short description of what you are actually doing? Are you trying to authenticate a) using OAuth 2.0, b) using an App Password, or c) using a Gmail user password with "less secure apps" enabled? Also, has this been working fine before?
by (120 points)
I am using Mail and password with server: smtp.gmail.com , Port : 465
implicit TLS/SSL (TLS 1.3,TLS 1.2)
All ciphers
by (120 points)
It was working successfully before 2-3 week but now showing this error

https://support.google.com/mail/?p=BadCredentials ay12-20020a1709028b8c00b001636d95fe59sm10917855plb.172 - gsmtp (535).
by (132k points)
Do you mean that you are using the Gmail user's username and password? Google stopped supporting this yesterday - see https://support.google.com/accounts/answer/6010255 for details. You will have to use OAuth 2.0 (see https://blog.rebex.net/howto-authenticate-gmail-rebex-oauth) or App Passwords (see https://support.google.com/accounts/answer/185833) instead.
by (120 points)
I've got help from your Solution => Mail_cs Project MailSendWinform
by (132k points)
The MailSendWinForm sample is fine. But since yesterday, Google no longer allows mail applications to authenticate using the account's password. The most simple solution is to enable two-factor authentication for the Gmail account, and generate an "App Password" for your application (or for MailSendWinForm) - in your code, you will then simply use the "App Password" instead of account password. To generate the "App Password", follow the instructions at https://support.google.com/accounts/answer/185833
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