Initial focus on warning dialogs should be on OK buttons?

[jikamens]

A user writes in email:

After the "send to outbox", on the "this won't go until you tell it" dialog, initial focus could/should be on the OK button. At present I'm not sure where it starts, but 2 tabs are needed to get to the OK. I know one can opt this dialog off, but I like to keep it as a reminder.

I actually need to think about whether I want these warning pop-ups to have initial focus on the OK button. If I put it there it might be too easy to dismiss the dialog accidentally before you get a chance to read it, something that happens to me all too often.