If you mean using link instead of a submit button then yes its possible.
I dont know what you want to send via mail, but whatever it is but it in a form somewhere:
<form method="post" action="(link to the page where you want to use the mail()-function)" name="mailform">
<input type="hidden" name="mail" value="(this is where you put the contents of the mail)">
</form>
Then in a link you put: <a href="javascript:document.mailform.submit()">Send email</a>
Then in the page where you send the mail, you will have the mailcontents in a $_POST['mail']-variable