The one "thank you" that feels the most sincere is the one that comes from you directly. When someone can hear you say "thank you" – just to them – it feels different. It feels personal. It feels authentic.
If you want to make an impact during this holiday season, consider calling someone or stop by someone's office and deliver that "thank you" in person.
Why? The "thank you" that is delivered personally takes more effort (and we know it) than sending off an email, mailing a card (except a handwritten thank you note), or announcing a thank you to everyone in your email newsletter. The "thank you" we can hear is even more meaningful.