There are all sorts of ways to check if the powder is bad. Open the container and if there's any rust or the powder is clumped, it's likely bad or going bad. Throw it out. Sometimes containers will swell or fall apart when powder goes bad.
If it isn't rusty and you don't detect any sharp, acidic odors it should be fine.
About a year ago, I ended up with a similar bunch of powder. The deceased owner had been a long time friend and was extremely careful to make sure the containers were clearly marked. All of the containers had lot numbers and some had dates of manufacture as well, usually the last two numbers indicate the year of manufacture. The lot numbers can likely be traced for more specific dates. Ganderite could likely tell us more.
Just for informative purposes I have powder on hand dating back to WWII, which I bought from Hodgdon's, 55 years ago. Hodgdon's had purchased it from manufactures as surplus and was selling it in 25 and 50 pound pressed cardboard containers, wrapped in white paper, with tar backing. Each container was stencilled with a lot number, manufacturer, plant, date, type and a few other things. I'm just using up the last of those powders now. The thing is, I'm still using loading data developed for them 55 years ago.
All of that powder was stored in large open sheds, resembling haysheds. Some of it had been stored like that for 20 years, before I bought it. I've been a bit more careful with it.
As for shipping the powder, you will have to adhere to special regulations and hazmat conditions. I believe there is a special shipping premium to be paid as well.
If you have a local gun shop, take all of the stuff you don't want there and make a deal to either sell it on consignment or trade for something from the shelves that you can use.
The other option is to pay it forward by passing it along to someone with limited funds that will put it to good use.