There is one guy at the post office that I try not to get.  I belong to a postcard exchange site and send lots of postcards internationally.  He told me that postcards to Mexico cost 69 cents when they are actually 72 cents.  Last time I went I asked for the 94 cent international postcard stamps and he tried to give me the 72 cent stamps.  I said those were for Mexico & Canada, he said "No, those are 50-something cents."  Shouldn't they learn the basics about the stamps they sell?

Many times, I don't put a return address on the postcards.  If one doesn't have enough postage what happens to it, especially if it is international?

They prolly trash em...sounds like to me you need to issue a complaint on this guy.

Postcards are first class mail and cannot be trashed.  If there is insufficient postage and no return address they are sent to a "dead letter" facility.  Not sure what they do with them there....  You are correct - international postcard rate is 94 cents except for Canada and Mexico. 

I would at least go to USPS.com and send an email to the station manager concerning the employee working the window who doesn't know the current rates.  The supervisor or station manager needs to know about this situation.  After all, if he is getting something this simple wrong - there is no telling what else he is getting wrong!!!

The postage rate changed in May. International changed from 90 to 94 cents. Canada and Mexico from 69 to 72 cent. There was a different rate for postcards in the past but not anymore. The clerk should know the correct rates but it is difficult to remember all the information required for the job. If not sure they should be looking it up. Is the clerk just having a senior moment and recalling an older rate?

The postcard may just go through without being caught with not enough postage. If it is going here in the USA, it will arrive postage due. The dead letter office will shred undeliverable postcards.

You can check the rate yourself and just ask for stamps in that amount without saying the reason. You can order stamps by mail from your carrier or online (dollar service fee). I can get the stamps and mail them to you if want.