Alright, there are many questions here:

1. Are you running on Windows, Mac, or some Unix variant? Your mention of folders implies Windows...
2. Perl can send mail, or it can call an outside program to send mail.
3. Sendmail is an outside program to send mail on unix-like systems. It is not a folder/directory, it is a program.
4. See the answers in How do I send e-mail from my Perl Program?
5. Please be more specific in the future. What does the program you are running look like? What errors does it give you when it doesn't work?