Love Letter is a popular game designed by Seiji Kanai and published by Tempest Games.
The game has recently been acquired by Z-Man Games but the F2F rules are still available on the Alderac website.
These postal rules by Richard Smith and Tom Howell.
Card images by Konstantin Sokolov, full download on BoardGameGeek
1. The game is for three or four players and there are thirteen hands played simultaneously. Player order is determined randomly. Each player receives 13 hands of 1 card, or 2 for the hands for which it is his turn to play.
2. In a three-player game at the start it's player 1 to go on hands 1, 4, 7, 10 and 13; player 2 on 2, 5, 8 and 11; player 3 on 3, 6, 9 and 12.
3. In a four-player game at the start it's player 1 to go on hands 1, 5, 9 and 13; player 2 on 2, 6 and 10; player 3 on 3, 7 and 11 and player 4 on 4, 8 and 12.
4. Each postal turn the play moves round one position to the right, so player 2 now is going on hand 1, player 3 on hand 2 etc. Note that if the next suitor round the table has been eliminated from a hand he is skipped. A new card is then drawn for the active player on each hand.
5. In the event of an NMR, for each hand one of the two cards is selected at random unless one of the cards is the Princess (play the other card), or the two cards are the Countess and King, or the Countess and the Prince, in which case the Countess is automatically discarded.
6. If a player's orders cannot be implemented the GM may decide to ask the player to amend. Alternatively, if a card is played against an opponent with an active Handmaid, the next valid player around the board is the recipient, and if a Guard is played and the player nominates Guard (or fails to nominate) he will get a random non-Guard card type selected by drawing from a full pack.
7. There can be up to 11 postal turns (4 players) or 12 (3 players) - there are 16 cards in the deck, but remember that in each hand the GM sets aside 1 card at the start (this is only used if a Prince is played on the final round).
8. In each postal turn the previous turn's actions are resolved and hands updated as appropriate. Note that the turn report will show played / discarded cards as these can be a tie-break on determining who gets the token, and are (obviously) useful when playing a guard.
9. The card discarded by the Prince goes face up on the victim's pile, and when the Baron is played the loser's card is turned up (the winner's remains secret but everyone knows it is bigger than the loser's). When a spy is played the player is informed secretly of the victim's card.
10. The first suitor to get five tokens (3-player game) or four tokens (4-player game) marries the princess and wins the game, which ends on that turn.
Andy, Bert and Carl are the players vying for the princess's affections.
HAND 1: Andy has "drawn" a card (giving him two) and must choose one of these cards to play. Bert and Carl each owns a single face down card. Andy has a Baron and a Guard to choose from. Playing the Baron would be a very bad idea so it has to be the Guard. His orders are "Play the Guard on Carl and guess that he has a Prince". Bert and Carl do not submit orders for this hand. In the turn report the GM states whether or not Andy is correct - if so, Carl is eliminated from hand 1, if not Carl survives and his card is not revealed.
HAND 2: Bert has "drawn" a card (giving him two) and must choose one of these cards to play. Carl and Andy each owns a single face down card. Bert has the Countess and the King, and so is forced to play (discard) the Countess. Carl and Andy do not send orders for this hand, but after seeing the turn report know (for rounds 2 and 3) that Bert's face down card is likely to be a Prince, the King or the Princess (unless he's discarded the Countess as a bluff) so if one or both of them has a Guard he's at increased risk of elimination.
HAND 3: Carl has "drawn" a card (giving him two) and must choose one of these cards to play. Andy and Bert each owns a single face down card. Carl has the choice of a Guard or a Spy. He decides to play the Spy on Bert. This choice of action appears in the turn report but not the outcome - the identity of Bert's face down card is emailed to Carl along with his cards for the next round. If in round 3 Bert does not play the card he is known to hold then he's in trouble for round 4.
HAND 4: It's Andy to play and his orders for this hand are sent to the GM along with his orders for hand 1 (and any other hand on which it is his turn to play in round 1).