This isn't something I'd pick out, but since it was mentioned, it bugs me, too. There's no reason to abbreviate "before" as "b4" on a web board where there is no character limit to your messages. Maybe it makes sense in text messages on cell phones or something, but not in general. It saves very little time and can make things harder for others to read. I know that it takes me longer to interpret heavy use of chat-speak than properly written English. I don't think anyone's expecting perfect English 100% of the time, but you should be able to write a proper, coherent message that will be understood by everyone without needing chat-speak stuff.
Anyway, as for the original question, I believe that if you store tea properly, it can last a pretty long time. Black tea, being the most oxidized, will probably suffer the least from exposure to air. You'll still want to avoid it as much as possible and keep the tea in a tightly sealed container in a cool, dark place. The tea should lose some of it's flavor over time, but exactly how long it will take for you to notice the change, I don't know. Proper storage should go a long way to keeping the tea as fresh as possible for as long as possible.