Every important document ever in my life arrived via "snail mail" so I can't really imagine anyone not taking it seriously. Except maybe some odd internet whiz-kid with a propeller hat.
They'd only be working with people that take snail mail seriously.
If you have tax problems, the I.R.S. will not e-mail you. It will not call you. It will not text you. It will not contact you on Instagram, Facebook, Twitter, YouTube, Slack, WhatsApp, or any other digital method.
Of course, but a letter saying "we're going to take your bling away" is likely to elicit a different response to "we want to ask you some questions about your internet usage"