Outlook 2003 and 2007 support a maximum of one mail account per mail profile. As such, the Outlook Add-In for these versions of Outlook supports a mail profile with a single mail account.
Outlook 2010 and later supports mail profiles with multiple mail accounts. The Outlook Add-In seamlessly works with this new feature and (from a user standpoint) there is no real difference in how the Add-In is used. Emails with attachments can be sent from any of the mail accounts in the profile and the Add-In will manage the emails that meet the policy criteria, as usual. If an email is sent with the download notification feature turned on, the notifications will be sent to the account from which the email was sent. The Mail Express Status pane will show an aggregated view of all packages that are being managed by the Add-In for all accounts. If an account is disconnected from its mail server, the Add-In will wait until connectivity is re-established for that account before uploading commences.
The Outlook Add-In is supported with the following mailbox types:
Outlook 2003 supports MAPI only
Outlook 2007 supports a single MAPI or POP (not both at the same time)
Outlook 2010 and later support MAPI and POP