The From field in a meeting request does not list all accounts in Microsoft Outlook
Original KB number: 978809
Symptoms
When you open a meeting request in Microsoft Outlook 2010, Outlook 2013, Outlook 2016 or Outlook for Microsoft 365, the From field does not list all accounts. Therefore, you may be unable to switch to the account that you want to send the meeting request from.
Workaround
To send a meeting request from the correct account, close the meeting request. Then, switch to the calendar for your intended account before you create a new meeting request.