I was reading a post in a LinkedIn group in which the author recommended against sending handwritten thank you notes.  This person said they are old fashioned and slow.  

I have to disagree (though not 100%).  The handwritten note is often  the way to go.  Here's why:

1) People are deluged with emails.  Many people stay up late processing the work-related emails they didn't have time to answer at work. Who needs one more? 

2)  Emails are often not reliable.  They can get caught in spam filters, deleted unread, or just sit in someone's inbox unread. Look over people's shoulders when they're reading email and notice how many have never been opened.

3) A handwritten note, especially on a nice card, is refreshing and different. Most people send emails these days.  Can you even remember the last time you received an envelop in the mail addressed in  pen? Weren't  you curious to see who it might be from?

4) A nice handwritten card or note can provide a warm touch (of course, this assumes that you have good handwriting. If you Don't, type it).

5) If you send it by US mail, you can also enclose something to follow up on your conversation. For example, you might send a cartoon or an article that might be of interest, based on your conversation.  Of course, you could send it with an email attachment, but who wants to download something, if they Don't have to?  Many  companies do not allow people to download attachments for fear of spreading viruses.

Email definitely wins in terms of speed.  If you want it out fast, you can send the email and the card too.  In a game of inches, the little things sometimes make the difference between winning and losing.