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 email@example.com (default account) and firstname.lastname@example.org configured, when email@example.com is connected to the server,
you cannot get firstname.lastname@example.org
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:
For detailed steps, visit Use
Windows PowerShell in Exchange Online .
2. Run the cmdlet that resembles the following.
Please be noted that email@example.com is
the default account in Outlook.
$target_giving = 'firstname.lastname@example.org'
$user_getting = 'email@example.com'
$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 http://community.office365.com/en-us/f/160/t/3505.aspx .
Have you tried using the Windows transfer wizard to transfer them between profiles? THink of the old and new profiles as computers, and you can just transfer them accross.
Does anybody know why this happens with 3 mailbox on the same Outlook, but is only with a few PCs, in others PCs everything is working fine.