Well an auto-responder would work if you sent in a sample by email, but what would you get out of that other than knowing that the sample was received. Previously the only time you got any response was if they needed more information.
The new submission method (from the chest) isn't emailed, but uploaded directly to Alwil, so they may not even know your email if you added one. So for new samples there is I believe an element of automation (analysis) to determine if it is considered malware and if so what priority to assign to its further analysis and inclusion in the VPS Updates.
avast are usually quick to correct identified and acknowledged FPs, so periodically scanning the file from within the chest (after a VPS update), when it is no longer detected it has been corrected and an update maid to the VPS. When it is no longer detected you can Restore it from within the chest to the original location.
For new samples, you can add the file to the User Files (File, Add) section of the avast chest (if it isn't already there) where it can do no harm and send it from there. A copy of the file/s will remain in the original location, so you will need to take further action and can remove/rename that.
Send it from the User Files section of the chest (select the file, right click, email to Alwil Software). It will be uploaded (not actually emailed) to avast when the next avast auto (or manual) update is done.