Error: SMTP error: could not authenticate

What's Causing This Error

This error indicates that the client could not authenticate with the email server. It can be the cause of multiple reasons, for example:

1. The user did not enter valid credentials when logging in.
2. The user did not verify with the multi-factor authentication mechanisms enabled.
3. The user did not have the correct SMTP settings configured.

Solution - Here's How To Resolve It

The user may follow the steps mentioned below to resolve the most common issues that could cause this error:

1. The user must check if the credentials in use are valid.
2. The user must make sure that they complete all multi-factor authentication challenges.
3. The user must make sure that the client configurations contain the following valid SMTP configurations:
4. SMTP server address
5. TLS Port number (if applicable)
6. SSL Port number (if applicable)