Hello Leanne

WP Mail SMTP Pro doesn't redirect the URI correctly. They need to check if it's their scope or not, but they're not doing that.

Please go to ..wp-content/plugins/wp-mail-smtp-pro/src/Pro/Providers/Providers.php and find this method:

process_auth_code

You need to add this to that method:

if (explode('-', $_GET['state'])[0] === 'amelia') {    return;
}

Like this:

You will need to save my response when WP Mail plugin gets updated, so you can do it again.

You're welcome, Leanne

If you have any further questions or issues, please feel free to open a new ticket, and we'll gladly help.