Gmail smtp error

Some apps and email clients doesn't meet Gmail security standards , they use less secure technologies to log you into Gmail account , and servers blocks these requests by default. In these cases, you'll get a message related to the security of the email client.

Unable to send mail through smtp.gmail.com

Earlier, in order to resolve this issue, log in to Gmail account through a web browser and enable access through "less secure apps". Up to May 30th, 2022, it was possible to send emails through Gmail SMTP with this setting turned on. After that, users started noticing that apps such as Outlook, Thunderbird, and other third-party email clients started prompting them for their Google passwords. When they would re-enter their Google password, it would get rejected saying it was incorrect. It is because Google no longer supports the use of third-party apps or devices which ask you to sign in to your Google Account using only your username and password.

An alternate solution

If your email program is incapable of using this new approach to authentication, there is a possible workaround.

1. Turn on 2-Step Verification
2. Use an App Passwords

The app password approach is probably the easiest, but it'll require you to set up two-factor authentication.

Turn on 2-Step Verification

With 2-Step Verification, also called two-factor authentication, you can add an extra layer of security to your account in case your password is stolen. After you set up 2-Step Verification, you can sign in to your account with:

1. Your password
2. Your phone

Enable 2-Step Verification

1. Open your Google Account.
2. In the navigation panel, select "Security".
3. Under "Signing in to Google," select 2-Step Verification and then Get started.
4. Follow the on-screen steps.

Create & use App Passwords

If you use 2-Step-Verification and get a "password incorrect" error when you sign in, you can try to use an App Password.

1. Go to your Google Account.
2. Select Security
3. Under "Signing in to Google," select App Passwords.

1. At the bottom, choose Select App and choose the app you using and then Select device and choose the device you’re using and then Generate.
2. Follow the instructions to enter the App Password. The App Password is the 16-character code in the yellow bar on your device.
3. Tap Done.

How "more secure apps" help to protect your account?

1. Which level of access you're giving the client before you connect your Account.
2. Client access only a relevant part of your Account, like your email or calendar.
3. Connect your Google Account to the client without exposing your password.
4. Disconnect your Google Account from the client at any time.

OAuth 2.0

OAuth 2.0 is the industry-standard protocol for authorization. When you sign in with OAuth 2.0, you sign in to Google's system directly. In OAuth 2.0 , you authenticate directly to Gmail with your credentials and authorize an app to do certain things. The third-party app only sees an authorization token provided by Google as proof that you authenticated correctly and agreed to authorize that app.

There are few reasons this is important:

1. By controlling the login form, Google can limit and monitor attacks attempting to discover passwords via brute-force login attempts.
2. Controlling the login form also allows Google to protect you against a malicious or incompetent app that might not handle your password in an appropriate way.
3. You don't have to share a password that, let’s be honest, you probably re-use at every other internet service you have.
4. By tracking tokens, Google allows you to revoke tokens for compromised devices or applications.