Launched over fifteen years ago, Gmail has grown from the "new kid on the block" into a position of prominence. Depending on what data you look at, you might even see Gmail as the #1 mailbox provider, at least here in the US.Gmail's spam filtering systems incorporate user feedback and engagement. And they know what they're doing. If you are not sending wanted mail to people who requested that mail and who read that mail at high enough percentages, you're going to struggle. You won't reliably get your mail to the inbox. Their systems are too good -- their magic spam fighting robots look at metrics very closely -- and their view of certain metrics can even change over time! What got you to the inbox in 2016 might not be good enough to get you to the inbox in 2020. Deliverability success at Gmail requires not only that you adhere to best practices, but it also necessitates ongoing monitoring and tweaking of your marketing program.
It was originally called Hotmail. You might call it Outlook.com. I suspect the best name might be "Microsoft OLC" (Outlook Consumer), as this appears to be one of the names applied to this email platform internally at Microsoft. Whatever you call it, successful inbox delivery can be a bit of a challenge, as this webmail provider can be quick to block senders that may not have issues elsewhere.
