Text messages don't always send; I get a red flag message. How can I make them re-send automatically?

This drives me nuts: Occassionally, but not often, I will send a text message and it does not go through. This happens both when I am using iMessage or regular text messages. It gets me into a lot of trouble: I assume my text message has gone through, then check my phone half an hour later and realize the message has not been sent. I don't even get a vibration or a notice that it hasn't sent; it's only when I check my messages that I see the red flag but my undelivered message.
How can I get the iPhone to just automatically keep trying to re-send these messages until it goes through, or at the very least to give me a notification buzz when the message doesn't go through so I know to manually re-send it myself?