>Many of you know that we have one company email address here at TPM. It’s the one linked at the top of the site. It’s the lifeblood of the whole operation.
I also know from personal experience they used to send newsletter/marketing/transactional email from the same address, which you should never do. They probably got a little spammy with some marketing or newsletter emails and got their domain blocked by Spamhaus or another intermediary, and like every other ESP google has automated systems to blanket ban when they see you pop up in a spamhaus list. Pretty simple.