Email is not sent due to failed authentication:
Authentication failure [SMTP: Invalid response code received from server (code: 535, response: 5.7.8 Error: authentication failed: another step is needed in authentication)]
This error is caused by your SMTP server using a different type of authentication method.
By default, the plain authentication method is used in our application.
You can either permit the PLAIN authentication method on your SMTP server, or configure another authentication method in PAP > Configuration > Mail accounts > SMTP settings. Here, you can select the authentication method to be used when connecting to the SMTP server (please consult your server administrator for assistance).
To elaborate, authentication to the SMTP server can be performed using the following methods: CRAM-MD5, DIGEST-MD5, LOGIN, or PLAIN.
If you are unsure which authentication method to use, or if changes to your SMTP server configuration are required, always consult your mail server administrator before making modifications.