Accurate number of stamps on your envelope

[purpleyes]

I was just wondering, does USPS throw your mail because of lack of stamps like only putting one stamp instead of two; or do they send it back to you?

[Joey]

USPS won't just throw away mail because it doesn't have sufficient postage. They will either send it back to you or deliver it with a postage due notice. I don't know what is more common.