The day after a reception, french people often send a thank you card to their hosts or guests. After a weekend or a holiday in your friend’s home for example, send them a short letter or a “Lettre de château” in the week following back home, is the best way to emphasize the pleasure you had during your stay.
The how to express his gratitude may vary depending on the type of reception and also on the degree of intimacy that we have with our hosts or guests. If you know them well, you can express it by a phone call; and you must do it the next day; but if your relationships are less intimate, preferably send a card or a letter; you can sent it within the week after the event.
The text can be short: it is not essential to rave about the beauty of the place or the excellence of the cuisine … The great art is to write a sincere letter; an original thanks, so, you can be warm but natural !.
Some french words of thanks… « Je te remercie beaucoup, Je vous remercie très sincèrement, Je te remercie infiniment, Je vous remercie de tout mon cœur, Je tenais à vous remercier sincèrement, un grand merci pour…, c’est très aimable à vous, mes plus sincères remerciements, … »
At work we must thank after a promotion or obtaining a distinction. It is very common to thank its guests after a wedding, for a baptism or a birth’s present also. You should remember in your card, how pleasant was to share this special moment with them and do not forget to thank for the gift they offered you. If you do not send a “remerciement”, you risk being taken for an impolite person.
If you have accepted an invitation and finally you cannot attend it, send a note of apology the next day. If you expect to be invited back, do not forget to make the invitation within two next months.