Currently, we can only access the `bcc` property of a Mailbox Item if we are in the Message Compose context. This usually makes sense, since when we're in Message Read mode, we're probably reading em...
We also like to have BCC property in Office.MessageRead component of Offfice.js https://learn.microsoft.com/en-us/javascript/api/outlook/office.messageread?view=outlook-js-preview .
We want to read the BCC property from a sent e-mail to record to which recipients the mail is sent.