Re: Email forwarding for Gmail users
Actually it's a thicket of standards, with sometimes spotty support beyond the basics.
Despite an occasional hankering for pine and having rebuilt a small ISP's SMTP and POP3 servers in about 1996, my recall is that GMail was a bit of a revelation when it launched. A nice big inbox, decent search, free, great anti-spam, efficient UI and generally rock-solid reliability. The alternatives were either expensive and a bit clunky (I migrated from Fastmail, which fell into that category), Squirrelmail from a vaguely shady web hosting company that probably didn't even RAID its mailboxes, or hosted Outlook Web Access (enough said),
And those were simpler times. Any email service now has to deal with a firehose of spam, phish and worse hitting my email address that's been in continuous use over nearly quarter of a century. I don't know what magic GMail is doing to sort everything into the right folders, but I bet it helps being able to hire the best data scientists and pointing them at a substantial fraction of the world's email flows.
It has to be able to defend my inbox against sophisticated attackers. I know GMail is pretty good at this, because they carefully warned me my account was under nation state attack a decade or so ago, and encouraged me to turn on two factor back when they were one of very few consumer services offering it.
And because of what spam has done to the email ecosystem, players need to be important enough to sort out deliverability issues with the big boys who host most of the worlds mailboxes when they occur.
So I'll probably stick to GMail + Cloudflare ARC-compliant mail routing. Seems to work nicely on a test domain - SPF/DMARC/DKIM all pass.
However, I'm all ears if you have better options.