In other words, check the collection times on the blue USPS collection boxes and drop your mail not far before those collection times, and never late at night or on days no collections are made from a box.
However, if everyone pursists in that, the thieves will likely change their activity to daringly raid the blue boxes in the last half hour before their last collection times. Likely they’ll even have a fraudulent USPS decal on their vehicle.
I always just include the post office on my daily errands when I must make a mail drop to them, which is not very often at all. They also have a blue box outside, but it is under an obvious surveilance camera.
That's pretty much how I do it. Can't just put outgoing mail in the home mailbox and put the flag up, not for a long time around here.
How in the hell can someone get into the box through the access door? It seems to me that they could just have a mail slot, about 10 inches by 3/4 inch. Nobody could possibly get into it. Let me design it, very simple.