If you can find the main place it escapes (under front door, a window, whatever) place a bucket of Ona gel there, it will get sucked out with the smoke and does a good job covering odors. I love the smell of ona, good shit.
Or as mentioned above, an ozone generator by the leak, I have one behind my couch to keep my living room from smelling like a Tosh hotel room
hmmm, i always feel suffocationphobic when im in the tent with the thingy shut for negative pressure...i stand in there sometimes to see which vent the air is coming thru mmost prominently, as i only want it to come in thru the bottom 6" duct that comes in from outside, really cold usually, keeps it a nice mid 70's. but i still dont like being in the tent...there's edibles
get in your tent, or buy a scrubber and blow the smoke into the fan ( I use to do this for a while in an apartment )
I recently put a carbon filter on the intake fan of my computer. BAM instant recirculating carbon filter in my room. I blow my hits at it and they get sucked in...doesn't work 100% but it sure cuts it down alot.
If I'm feeling extra paranoid I use a long tube with the dryersheets...looong tube like 4 feet, a shorter tube never worked good for me. It's also important to change the dryer sheets out every week or so and insert them properly into the tube so they actually filter the smoke rather then the smoke just traveling around them...but I only use that on special occasions like if family or w/e is coming over, and I swear by it.
...also you could smoke in the growroom utilizing those filters maybe?
*edit .. as for the mail slot duct tape a garbage bag or something to the inside so the mail drops into it...or something like that..I guess you have to get the mail out somehow ... but I'm sure that will help you figure out a better idea...just make sure someone doesn't come over and be like "WTF is a garbage bag doing duct taped to your door?" think ahead...ppl can tell when you're making shit up on the spot.
Lookup ozn-jr it releases 200mg/hr and does 10 minute Intervals on/off
hook it up so it's inside the vent that is pulling air OUT of the room so it removes leftover dirty air.