Send e-mails with GMail
To send e-mails with GMail, you have to use this configuration:
SMTP server: smtp.gmail.com
Connection: Full SSL
[x] Perform SMTP Authentication
POP3 is not required
In your Google Account (section "Security"), you have to enable the option "Allow less secure apps". Otherwise GMail will not accept logins to your SMTP server.
If you use 2-Step-Verification in GMail, then you have to use an App Password. That means that you have to enter an App Password into WebSite-Watcher instead of your regular GMail password.
More information about app passwords can be found at https://support.google.com/accounts/answer/185833