To allow an Exchange user to send from an external e-mail address, perform the following steps:
Get-MailContact MyUser@MyExternalDomain.com | Add-ADPermission -User MyUser@MyLocalDomain -AccessRights ExtendedRight -ExtendedRights "Send As"Replace the first e-mail address with the external one, the second part contains the user you wish to assign the permission to.
By default, Thunderbird shows the namespaces of IMAP folders as a seperate folder containing the subfolders belonging to that namespace. An example of this is when you use Google Mail and have IMAP access configured.
An add-on exists for Thunderbird which gets rid of the namespace folder and sorts all subfolders in the root tree:
This is particularly useful for Google Mail where the sent mail, trash and other system folders are stored in a namespace called [GMail]. This way, these folders are stored directly in the root of the tree rather than in a subfolder named after the namespace.