The envelope of the invoice is metered as "first-class pre-sorted." This is surprising. The volume needed to get a .347 cent/piece discount is huge -- many thousands of pieces of mail for a single mailing. I mean, they're not American Express or Citibank who have huge daily mailings (tens of millions per year) of billing statements.
Nearly unheard of for an IT company to send a post-mail statement/invoice. The costs are huge when you add it up.
Nowhere does this document say "invoice" or "statement" or "amount due." These terms have legal meaning whereas "account summary details" does not.
Also, if you go to there online login form, click forgot password, and then enter the account number along with ANY email address, it says "We haven't yet received your payment. Please visit the Support Page for assistance."
Clearly, this is a scam with intent to deceive. I think they have avoided blatant violations of law, but the intent to deceive is clear based on various factors (the document, the method of mailing, etc.)