If someone takes you out to eat or to an event, gives you a gift, or does you some kindness, the rule is you always write a thank you note.  That’s a card, handwritten, in an envelope, and with a stamp – and sent through the US Mail.

Now, like any other good lawyer, I’m going to tell you when you can break the rule.

In my opinion, you can send an electronic thank you (via Facebook, email, Twitter, whatever) so long as an invitation and all correspondence related to an invitation was done through that medium.While I think that any gift requires a physical thank you note, if your relationship is primarily an electronic one, I think an electronic thank you is OK.

You can send an electronic thank you if you don’t know the person’s physical address.

You can send an electronic thank you if time is of the essence (e.g., you interviewed for a job, and you suspect the decision will be made very quickly – not enough time for a physical note to arrive or make an impact).

The only time you don’t have to say “thank you” is if you are me, and your estranged parents send gifts to your daughter (addressed to her, with cards written to her) for her birthday and Christmas (sometimes, when the fancy strikes them – and it’s never clear when that is), though they never make any other effort to have a relationship with her – and you have had enough.  Then, screw the thank you notes. (I’ll still feel guilty for not sending them, but only fleetingly.)