Greetings, AdrianJ217.

It's difficult to provide detailed responses, without more information from you. But w/o that information;
On a UNIX-ish platform:

# see if sendmail exists, and where it's located
$ which sendmail
[download]

if true, you will be able to use, or create a Module that utilizes the capabilities that the Sendmail MTA provides; else, discover the installed MTA, and if any, what it provides.
Do note, as has been rightfully noted in other replies; you run quite a risk, providing an email form in the wild. If abused, or not properly secured, you can be 1) overwhelmed by SPAM. 2) Have your box HACKED. 3) become BLACKLISTED.

There are ways to prevent the potential pitfalls of using an email form in the wild, and many of the Monks here could easily help you overcome them. But without greater detail on your part. It will be difficult to advise, or provide direct details.

--Chris