Stamps

I don't like stamps.

When you need them, you don't have any.
When you are to buy them, you either don't have enough money, or there are none to buy.

I don't like post.

When you are expecting something, it takes forever to come.
When you want to send something, you either don't have stamps or envelopes.

I don't like messeges.

When you want one, you don't get one.
When you don't get one, you'd like one.
And when one finally arrives, you don't like the content.