Should I have any concerns about sending containers containing alcohol through the u.s. Postal system?

You might have some issues. They could potentially charge you about 15$ extra for the shipping for “safety precautions.”

Is it neccessary to tell them the contents of the package when I ship it?

I don’t know.

I think they’ll ask what’s in the package when you ship it. They ask if there are any potentially hazardous materials or foodstuffs, I think.

they might refuse to ship it based on a states alcohol laws, we have restrictions in Oklahoma.

We have restrictions in Louisiana also

Mailing liquids is prohibited (down at the bottom) and they do ask you if your package contains x, y & z prohibited items. Of course, you could lie. I’ve known of instances where people have gotten away with it. I don’t know about private carriers (UPS, etc), but I recommend going that route instead.

you could always call the post office and ask anonymously and see what they say.

Yes..cannot mail..must UPS.

Found this out a few years ago when I wanted to send some wine to an out of town friend.