Look at the orange barcode . . . . it's on the bottom of the envelope, so it made it through automation correctly . . . This envelope looks exactly like someone put their finger under the flap, and ran it down the length of it to open it . . . .
. . . and if it got jammed, the envelope would have vertical creases in it . . . .
. . in addition . . . automation jams don't usually delay mail - they are cleared out immediately, and sent on their way . . . if it was delayed a couple of days, as Hog said, it would be indicative of a misdelivery . . . .
Unfortunately, though, he will never know for sure . . . with his carrier handling about 3,000 letters on the day after Columbus day, the odds of him remembering this one particular letter are slim to none . . and if the carrier recieved it like this, there is no way he will ever know where it came from . . . it could have even been originally misdelivered by a different carrier on a different route . . . . in fact, if the mailer sent out a large quantity, there's a chance that glue on the back flap of one letter caused it to be stuck to his letter, and the carrier that delivered it never even saw the address on the front . . . I see that at least once a week . . . .
At the very least, Hog, I can tell you, regardless if the error was from automation or misdelivery, there is no worry that your letter was intentionally opened by someone at your post office . . . The only party ever allowed to intercept a first class letter would be a postal inspector, with an order from a judge, and if they did so, it would not have been done in that method . . .
If you're still worried about it, bring it to the postmaster for him to record it . . . he may be able to tell you if there was a substitute carrier on recently, who may be more likely to deliver something in error . . .