They say that how you close a dinner party is just as important as how you begin it. To host guests and then not conclude the evening with a proper goodbye and an escort to the door is rather faux pas at a well put together dinner party. It is important to send your guests off as warmly and sweetly as you welcomed them in earlier in the evening.
However, your duties as a host do not end once you've walked your final guest to the exit.
Even though it was you who slaved away in the kitchen cooking, and spent the better part of the day cleaning and setting up, and will spend the rest of the evening tending to a sink full of dirty dishes, it was the presence of those guests that turned your home into a dinner party. Therefore it is important to send everyone a quick note the next day to remind them how they contributed to the special evening.
One of the most powerful tools you have as a host is the ability to make your guests feel appreciated. Many times a guest will leave a dinner party feeling guilty that they didn't help to clean, and feel bad about how much work the host put into the evening, but this is your chance to remind your guests of how much joy they brought you by allowing for this evening to transpire.
A thank you note after a dinner party does not have to be formal. There is no need to breakout the inkwell and follow a calligraphy workbook. It can be as simple as a text or an email. A basic note like "Thank you so much for coming last night, it wouldn't have been the same without you" is always a foolproof message to send, however I always recommend trying to make your note a bit more personal. Did that guest bring wine or a dessert? Definitely thank them for that specific item. Did they bring a gift for the host? You better thank them for that! Did they brave a rainstorm/ snowstorm/ heatwave/ outrageous subway delay just to get to your apartment? Thank them for preserving through the elements to make it to your home.
I recently read in the book Brunch is Hell: Saving the World one Dinner Party at a Time (my new favorite read) that a New York Goodbye is when "Five minutes before the party begins, a guest sends you a text saying she can't make it, she knows she;s the worst, but let's catch up soon".
In this day in age there are a million of lame excuses people use all the time now for not showing up to things: it's cold, there's a new show on Netflix they need to finish, they don't want to, something better came up.
Therefore, those people who actually followed through and committed to your dinner deserve more than just a goodbye hug at the door and perhaps a Tupperware of leftovers. Remind them of how glad you were to host them, and who knows - maybe in a few weeks they'll be inspired to cook for you.