But if you are sending money to a charity and they sent you those envelopes please place a stamp on the letter. It is just a few cents but that is a few cents they can use towards the charity instead of that letter.
I always do this.
Not very good advice. An envelope is too small. Get a huge box- largest size you can send regular mail. Fill it with rocks or bricks and tape it up well. Tape the envelope to the box. Voila. An expensive lesson.
I don’t know that it’s petty or a waste of time. A stitch in time saves 20, and there’s likely no better way to make sure someone doesn’t junk mail you twice and waste your time than to do this. In fact this is part of the reason you see less of the self addressed stamped junk mail circulating. Similarly you don’t see many of those “fake check” junk mails either because someone actually cashed one and fought the ensuing legal battle and won.
I always do this.