Please, do not send me an e-card.
I mean it. For anything, ever, really. Under any circumstance. I don't care how cool/funny/awesome it is.
Because they take you to a site on the web (typically), they are also hard to differentiate between phishing schemes and malicious websites, and they undermine the best advice of security professionals everywhere: if you weren't expecting it, don't click on it! This particular issue makes it hard for me to understand why any corporation uses third-party sites: once you tell someone it's okay to click on a link from one third-party vendor, how do you tell them not to click on someone else's link, especially if it looks sort of similar?
No one, however, ever sends an e-card to be a jerk. Everyone does it because they are thoughtful. To which I say, "Dude, that's awesome." But I'd rather be a lonely e-mail address on a big BCC: list than a person whose e-mail got shared.
I really do appreciate the sentiment. But generally, I'd rather not know about the sentiment in this case. It's not about "bah, humbug" on the holiday spirit: it's really just about what an e-card site truly is. Spam.