System path to mail program

[Tamo]

Hi there all....I am setting up a mailing list program on my site.
http://www.elan-entertainment.com.

So far I 've set it up so that I can accept emails to my list but I can sent out mail to people on the list.

The script asks for "the system path to your mail program"....could you let me know what to put here please??

Thanks