you don't have to. Please, report the server operating system, and versions of php, and Tikiwiki that you are using, just in case. It will be needed when a more skilled user or admin (I'm not enough) reads your message to attempt to suggest a solution.
For me and many people, mail sending at the server side worked fine out of the box without any need to configure anything special.
The must be related to some previous bug on some smarty template (.tpl), I guess (but it's just a guess).
Can you try with the latest 1.9.8 code? (you can read where to download it from at http://doc.tikiwiki.org/Download )
And welcome to Tikiwiki community, by the way!