Unless Email::Filter is making the results taint-safe, you are passing unvalidated data directly to a shell. Big time security no-no. It is better to open the file from within perl, and write escaped data to the file.
Depending on your mailer, you could also have a race condition on temp.log. Might be better to lock that file prior to writing to it.
Hey there. This was just an example of getting the address and subject and certainly nothing that I would use in production! ;)
The goal is for people to email firstname.lastname@example.org and get a report back on their email account. All I really care for is the email address to reply to and all the rest of the email is ignored. After this I can generate a report for that email account and email it back to the address.