Gmail accounts not validating through email plugin

Hello! I am using the email plugin for a contact form on a new website. The email address I am using is a standard Gmail account: However, there is a validation error, I have tested the system with other Gmail accounts and they also throw the same error. I have checked that IMAP and unsecured apps are enabled. The oddity is that if I use a Gmail account, so it uses the domain name and not, the email works fine.

The error being thrown is this:

Failed to authenticate on SMTP server with username "" using 3 possible authenticators. Authenticator LOGIN returned Expected response c ▶

The question I have, does anyone know if it is possible to use a address for SMTP email, or does it have to be a business account with an administrator?

Many thanks in advance