My parents always instilled in me that handwritten notes are incredibly important and I've done this since I was a young girl.
I never send an email or text as a thank you as I think it's extremely rude.
I saw an article about this very thing recently and thought it might be helpful.
Even though my sons groan everytime I ask them to write a handwritten note to their grandparents, I know I'm setting a good example for them that they will hopefully pass along to their children.
Some guidelines for creating a proper thank you note: keep it short and simple, write it by hand even if your handwriting is bad, start with a salutation, express your gratitude and specifically mention the gift, reiterate your gratitude, and be sure to send it promptly. - ABC News