In the past two weeks my colleagues have been exchanging a lot of Christmas and New Year's wishes and cards through the company e-mail system. I don't mind receiving such email, but I usually don't respond because "thank you, you too" doesn't seem useful. It doesn't seem like a response is called for.
On the other hand I don't send any kind of e-mails that are unnecessary because it feels unprofessional to me. Most of them are addressing all colleagues, copy-pasted and not very original. But enough of my coworkers send these messages that I wonder if I'm violating some unwritten rule or norm by not participating.
Is it generally expected that employees will send and reply to mass emailings of holiday greetings? Does it depend on culture, job title/function, size of company, something else? If the answer is "it depends", how do I find out if I'm expected to do so?