Smoke smell from neighbors smoking outside is smelt inside

I live in a row home (new build) in Philadelphia that we recently purchased about 6 months ago. My next door neighbors smoke outside their front door, just next to our front door. When they do, the smoke smell seems to travel into the home , mainly concentrated in the vestibule and nook area just behind our front door. The smell is also detectable in the bedroom directly below this vestibule/nook , and the room has a window that also faces the same area the neighbors smoke. The smell tends to linger for a day or so with infrequent smoking activity, but can linger for much longer with more frequent smoking activity.
I find this odd because I assume the home insulation should prevent this.

Any idea why this happens and how to address the smoke smell without engaging the neighbor re impact of their smoking activity. Thanks for your support re this concern.