Office 365 now supports sub-addressing

[LabanSkollerDefensify]

Remove "Office 365" from examples of mail providers which do not support
sub-addressing. They do since September 2020 [1] but configuration per
organization ("AllowPlusAddressInRecipients") is needed [2].

[1] https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=59441
[2] https://docs.microsoft.com/en-us/powershell/module/exchange/set-organizationconfig?view=exchange-ps

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[mackowski]

Awesome, thank you for this PR!