It was mentioned a couple times that there had been an occasional problem with bulk rate mail not being delivered by lazy post offices.
For those that do postcards, what type of postage do you use? Have you had any problems (that you know of) with your mail not actually being delivered?
The seminars were all at least several years old, if not more. Maybe there was some sort of crackdown and there's no longer an issue?
I've used the catalog mailer types of mail before, but not my own individual or co-op postcard/letter.