3c To4c Untagged Stamps On Envelope

If I use 1 40c stamp, plus several 3c or 4c stamps from the 1950s and 1960s that were released before tagging on a first class envelope to reach the current 55c rate, will that cause problems for the mail processing machines that read stamps?

If someone is able to fit 11 very small modern 5c stamps properly in a row on a first class envelope, will that cause problems for the machine?

If I pay a bill with these methods , I hope it will get there in time and not two months later LOL.

The presence of a single tagged stamp, regardless of denomination, should be sufficient to trigger automatic canceling. Of course, these days, canceling of stamps seems to be optional.

'
You are supposing that somebody cares.

Re-suppose, friend, re-suppose.

Of course, it can be worse when somebody cares:

https://goscf.com/t/3853

Cheers,

/s/ ikeyPikey