Email address vs account name - it’s important to be clear about mailbox type. Over the breadth of testing I’ve done I’ve set a lot of inconsistency between default / secondary mailboxes, email addresses containing dots (zzzz.xxxx@) migrated / not migrated and the possibility that test accounts (early migrations) might be flawed.
CTRL/V at the password prompt does work: it’s ultra stealth (no echo or cursor advancement) - just press enter afterwards.
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
