Mail is sent to firstname.lastname@example.org. An automatically generated
response is sent back to the user with an address of
"email@example.com". You can set the envelope sender to an empty
string. However, some programs will parse the message for the "From:"
field and send an autoresponse back to it. It is received at your
autoresponder, and you now have a mail loop.
This autoresponder also catches some other simple situations such as
mail from a mailer-daemon, empty envelope sender, bulk precedence
The patch http://shupp.org/patches/autorespond-2.0.4-2.0.5.patch included