I keep forgetting the correct way in which the username needs to be used when using IMAP to logon with your account to a shared mailbox. To logon to a shared mailbox you need to provide the domain first then / and then the account you want to authenticate with and another / then the shared mailbox you are trying to access. Below is an example. domain/accountThatNeedsToauthenticate/AliasOfTheSharedMailboxYouAreTryingToAccess