Plesk 12.x / Linux :: Protect Sendmail From Unauthorized Spam On Wordpress

In the past we disabled sendmail in Plesk to prevent spam from using the contact form of Wordpress sites to send unauthorized spam emails. Because of this, password reset emails do not work.

A few questions:
1. Is it safe to enabled sendmail for scripts in Plesk?
2. If its best to disable it, what is the solution for enabling Wordpress password reset without the need of using send mail?

One site was hacked, but I am not sure if Wordpress send email can be manipulated from outside the Wordpress site, or if it happened because the outside user brute forced their way into the admin to send these spam emails.Here is the Wordpress error that came up when resetting the password to a username:

The e-mail could not be sent.
Possible reason: your host may have disabled the mail() function.