Hi there and welcome!
I use a mailbox mod with my MES smoker for cold smoking the few times a year it gets cold enough in TX.
Honestly the mailbox mod wont really save you from bad smoke even with the
AMNPS. The issue is airflow so smoke gets stale.
Some MES electric smoker guys just put a little personal fan blowing sideways over the top of the vent and that draft causes the air to circulate and suck out of the smoker keeping the smoke going and never lingering to get stale.
I built a little cold smoking draft fan contraption to fix my cold smoke stale smoke problem.
It's basically a tube made of cardobard and a 12V computer fan I spliced into an unused 12v plug. The fan is angled up from the outside of the cardboad tube to blow air up the tube which sucks air/smoke up and out of my MES forcing a draft :)
I just set it over the MES vent hole at the top of my smoker and it drafts the smoke and air out, fixing any/all stale lingering smoke issues while cold smoking :)
Here is what it looks like:
View attachment 473434