Boomerang for Gmail is a really nice product - I recommend trying it if you haven't yet.
It give you a "Send Later" option in email, which helps if you want to write a reply but don't want it to go out yet - for instance, if you want to say "The blog post is live now," but the post won't be live for another three hours.
It's pretty cool. You wouldn't even realize how useful it is until you try it. Check it out.
Wow, I've wanted something nearly exactly like this for a long time. But for me "Send Later" is one of the lowest value functions (I think gmail already has a lab that does this). Instead I like an email re-appearing in my inbox if no-one has responded to it in a few days so that I can then follow up on it. Their email game seems pretty nice too, although I wish it had keyboard shortcuts as well.
With less than an hour of work, I bet you can modify the script to make exactly what you want. Actually, it seems that most of Boomerang's functionalities could be substituted for free with a couple of Google Apps Scripts.
It give you a "Send Later" option in email, which helps if you want to write a reply but don't want it to go out yet - for instance, if you want to say "The blog post is live now," but the post won't be live for another three hours.
It's pretty cool. You wouldn't even realize how useful it is until you try it. Check it out.
Edit: http://www.boomeranggmail.com