Each upgraded account can setup custom wedding emails using the custom domain name you chose. If you selected 'danielandsarah.org', you could setup 'rsvp@danielandsarah.org', or 'sarah@danielandsarah.org', 'rsvp@danielandsarah.org' and so on.
These custom emails get masked to your regular email so that all messages go to your every day account, no extra accounts to manage.