You might want to check into Mail::Bulkmail. It has a slew of nice features, is fast, etc. I have code that uses Mail::Bulkmail that I can share if you want to give it a try.

Executing sendmail directly can be risky and error prone.

/\/\averick
perl -l -e "eval pack('h*','072796e6470272f2c5f2c5166756279636b672');"