hwilms wrote:"Message could not be sent.Mailer Error: Could not instantiate mail function."
Technically, X3 itself does not (and cannot) send emails, but requires either the servers own mail() function, or the SMTP server (if defined). Some hosts (including yours) may have disabled the servers own mail() function, to protect it from being blacklisted for spamming.
Thus, your only option is to setup the SMTP option, which you can see is a checkbox in your MAIL settings. SMTP is better anyway, as it provides a legitimate way for you to send emails. It does of course require that you have access to an SMTP (normally bundled with your hosting account). Optionally, if you use GMAIL, you can normally setup GMAIL SMTP here.