You cannot connect two Office 365 accounts in one Outlook profile at the same time


Some customers find that if they try to configure two or
more Office 365 accounts in one Outlook profile, these accounts cannot all connect
to the Exchange Online Server at the same time, even though you have configured them correctly. For example, you have (default account) and configured, when is connected to the server,
you cannot get

This issue may occur intermittently.


To resolve this issue, use the Add-RecipientPermission cmdlet to add SendAs permission to the
default account. To do so, use the following steps:

  1. Connect Windows PowerShell to the Office 365
    Online Service


For detailed steps, visit Use
Windows PowerShell in Exchange Online


      2.  Run the cmdlet that resembles the following.
Please be noted that is
the default account in Outlook.


$target_giving = ''

$user_getting = ''

Add-MailboxPermission –Identity
$target_giving -User $user_getting -AccessRights FullAccess -InheritanceType

Add-RecipientPermission $target_giving -Trustee $user_getting -AccessRights

Note:  More details about Add-RecipientPermission


IF this method does not resolve this issue, welcome to leave a comment here, or follow up on the original post .