To help me to understand can you elaborate on what system you have sending out the emails? On the face it seems that the system could use any email address as the "sending" email without that email address being an actual address with any responses landing in a separate catchall address? There are some issues with email systems and how some spoofed email addresses are treated so you have to be a bit careful with that sometimes.
...turns out that my two cents is worth less or more depending on the current exchange rate.
roy darling *my posts seem a lot shorter in my head