When you're suffering from long-guest-list-itis, handling everyone's RSVPs can be a nightmare. Let technology do the work for you by setting up a Google submission form. There are even premade wedding RSVP templates ready to go. Just customize the fonts and color to suit your theme.
You can also set up your own wedding website through a site-creation portal like Wedding Jojo, Appy Couple, or Weduary, which all provide guest RSVP and management tools.