poolcritter
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Many services including Gmail silently ignore periods in localparts, so foo.bar and foobar are the same address.
Not about anyone (I'm openly agender), just had it in my downloads folder and needed to follow the rule.
overall we need something to text
pretty much Matrix's entire point
(plus send files)
also implemented in pretty much every server and client; I think even Element can send files
call
look into e.g. #matrixrtc:continuwuity.org — sable requires a setting to show the call button in non-DM rooms
video/screen share
unfortunately this is the only thing I'm not confident is supported
bonus for emojis, stickers
should be available with any im.ponies-compatible client such as sable
Not telemetry? Continuwuity just uses it to post release announcements to the admin room; I think there's a way to disable it if you prefer.
Thanks; didn't have it saved like that
Due to federation oddities, you'll need someone on your instance (such as yourself, by definition) to subscribe to begin receiving posts.
There's already Windows S mode — if you bought a device with S mode enabled, you need a Microsoft account to disable it.

SCP technically stands for Secure, Contain, Protect; however, the acronym is much more well-known.