i could not sand mail these error showing

Question

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

Answer 1

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?

Comments

I am using Mail and password with server: smtp.gmail.com , Port : 465
implicit TLS/SSL (TLS 1.3,TLS 1.2)
All ciphers

---

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).

---

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.

---

I've got help from your Solution => Mail_cs Project MailSendWinform

---

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