Whitelist to certain domains

[turt2live]

To prevent out-of-company people from using the bots

[Bubu]

A whitelist like mautrix-telegram has would be nice: https://github.com/tulir/mautrix-telegram/blob/master/mautrix_telegram/example-config.yaml#L316

That way allowing all users from my homeserver and some users from elsewhere would work.