At least in my experience, delays don't seem to get posted until about 20 minutes before boarding time, and this is calling the phone system. If they sent out an email 20 minutes before, you might not even get it until when you were supposed to be boarding. So I think they would need to fix the advance notice on delays problem first.

It takes some time, but I have found an accurate way to figure out delays (if departing from an out station or small station) is to figure out where your aircraft is coming from and see how it is doing against its schedule. If your departing from PHL,CLT,PHX you'll never be able to accurately determine where you aircraft is because they get changed to often. But if you departing from B34 in PIT on a 319 and you see a 319 is arriving into B34 from MCO, tracking the MCO flight can give you a heads up on delays.