I picked up the 4"duct fan yesterday and the needed hardware I'll try it this evening..I tried the muffin fan in front of the mailbox mod with no luck and inside the mailbox burns about an hour.. It's definitely an air, draft problem I left the tray outside the mailbox it burned the whole row ..
If it works outside the mailbox, that's why I think it will work if it's in the mailbox, and the fan is in the duct between the mailbox & the MES.
Picture this: You could have your
AMNPS sitting right outside of the Mailbox door, with the fan in the Duct. The
AMNPS would be working, because it's outside of the mailbox, and the Fan would draw the smoke through the mailbox & through the duct, to the MES, unless of course it is too windy. So all you are doing is sliding the
AMNPS into the Mailbox & closing the door, out of the wind. The fan should still be drawing the air flow around the
AMNPS, so it should work.
That's why I said it should be an adjustable speed fan----Turn up to get it going---Turn down once it's going to get a nice smoke flow to the MES.
PS: Make sure your top vent is fully open.
This is all just "Bear Theory"---Has not been tested previous to what You're doing.
Bear