It seems like many people have mentioned SendOut Cards. If you use them for birthday cards, do they get sent out automatically a few days before each recipient's birthday? Can you personalize them with a quick sentence or two?
Yes and yes. Of course, you have to tell the system to send the cards. But you can determine when they are sent. It would be a little more work if you wanted to say something different on each card, but you could certainly do that.