Greetings cards must not be sent out to mark numerous trivial events, or when a letter is more appropriate.
Humorous cards should be avoided, unless the recipient is very well known. Simple motifs and messages are more appropriate. Electronic cards are impersonal, unreliable and inappropriate.
Greetings cards can be sent on birthdays and anniversaries, or for special occasions such as Mother's Day and Valentine's Day.
They are also appropriate as a congratulatory gesture to acquaintances or friends, e.g. to the son of a close friend who has graduated from university.
Cards are useful if a number of people wish to send a group message, e.g. a farewell card for a colleague who is leaving that has been signed by everyone in the office.