Will the cost of postage for the millions of health insurance cancellations or rate increase letters going out?

No. I was informed that my rates are going up via the internet! seriously. I called to verify, and yes next year my premiums with BC/BS will go up 2/3 and my deductible will triple. Not my opinion. Oh I am so sure it'll be better care though. Ha! Any ways no postage was used. Very funny question though! I dig it.
@ Tom R: what the heck website did you go to? The phony one healthcare.gov? And how do you know giving your information to these people is safe. It turns out ANYONE can be a navigator and people (some, felons) are already using this as a data collection scam for identity theft.

Not significantly. A regular stamp is less than fifty cents. The insurance companies are probably sending the mail at the lower rate that applies to presorted bulk mailings. The total amount of postage involved is probably under a million dollars. A lot to a normal person, but insignificant compared to the USPS budget.

I think so.

No most of those same people would have received plan information from their insurance carrier anyway.
If anything the cancellation letters would be lighter than the plan books so the Postal Service may get less money instead.

uninformed I went to the website today and found I could get a policy for as little as 18 dollars so stay an uninformed republican. meanwhile I will sit back and enjoy yall eating your words.
by the way the post office problems stem from the gop. if they didn't have to 100% fund their pension they would be profitable. the gop is determined to destroy our country.