No Cancellation Of Stamps On A Cover

I have been curious about this for a while, but it triggered today that why does the situation occur in where I receive a piece of USPS stamped mail in which the stamps have not been cancelled. There are no markings at all to be found on the cover and it is a basic letter envelope. It just seems odd to me and conveys no record of having been transported through the mail, even though it came to me via California.

It's not unusual for some mail to get by the canceller and receive no postmark at all. It happens more commonly on unusually sized or shaped envelopes, those with bulges because of content (i.e. non-machineable letters, which are subject to a surcharge) and postcards.

Knupp - happens all the time. Soak the stamps off and give them another go.

Wt, that appears to be the issue as it is a bulgy letter. You would think that they would get hand stamped at some point.

Or if not hand stamped, then pen cancelled. Up here in Canada, letter carriers have permanent markers in their pockets and they're supposed to hand-cancel these stamps when they find them, collectors be damned.

Use the WD-40 method with a touch of cornstarch on the batch and reuse them.
Tom

I reuse 'em all the time. Have a glue stick right here on my desk. If Canada Post can't do their job, I'll take advantage.

Are these gummed or self adhesive?
Tom

Both, it has a modern Dennis the mennace and 2 older James cook stamps on it