The mail service story was interesting.
Alongside this, work continues to improve message deliverability and reduce the risk of outgoing mail being flagged as spam.
That means they’re learning how to play ball with the big, corrupt IP black lists and mail providers so their servers don’t get blacklisted just for sending lots of mail.
Email has become mostly balkanized. I can run a private email server for myself so long as I only send an occasional email. I read that if you need to send large volumes of legitimate mail you need to get multiple IP addresses to send from or you will be marked as a spammer. The big mail senders like Outlook and SendGrid are whitelisted because blocking them would trigger a deluge of complaints and users/customers would migrate to other services. That means people can use SendGrid to send spam and it will get through to average GMail users. You also don’t have to setup anywhere near as much verification for your mail domain when you send through them.