In OOTW, message opens new window on send but Janusseal App dialog not shown and item goes to Drafts folder

In Outlook on the Web (OOTW) for Exchange Online/M365, if OnSendAddinsEnabled is true in the user's OwaMailboxPolicy then the Janusseal App for Outlook dialog box is not shown upon send; instead the message attempts to open in a new window but soon after it closes and appears in the Drafts folder.

This issue is being experienced by other Outlook add-in vendors so appears due to a recent change to OOTW by Microsoft - Office.context.ui.displayDialogAsync "flash" dialog with onsend, but works if send is done from a popout window · Issue #2431 · OfficeDev/office-js (

Microsoft claim to have fixed the issue and that the fix is live -

The details of this KB article contain two workarounds (one of which avoids the issue for the end-user) if the fix has not yet reached your tenancy.

Article Information
known issue
fixed issue
Date created: 
14 Feb, 2022
Last updated: 
28 Feb, 2022 12:29
More Information: 

It appears that the intent of the property OnSendAddinsEnabled of a user's OwaMailboxPolicy has changed over time. Now in OOTW this property enforces that after clicking the send button the user should not be able to edit the original message and so OOTW opens the message in its own window -

The act of opening the message in its own window seems to be causing issues with Janusseal App for Outlook. Janusnet are unsure if this is due to a recent release of Janusseal App for Outlook or something that has changed in OOTW. The fix is to set the OnSendAddinsEnabled to false in the users' OwaMailboxPolicy.

Janusnet have tested setting OnSendAddinsEnabled to false, and after a short while of time and logging back in to OOTW, when the user clicks the send button the message does not try to open in its own window and Janusseal App for Outlook's dialog starts and operates as expected.

Immediate workaround for end-users:

The end-user can double click on the message in the Drafts folder to open it in its own window. Then when they click the Send button the Janusseal App for Outlook classification dialog should be shown and operate as usual.

Alternatively, while composing the message they can use the button in the upper right corner to "open in new window"; again this will allow Janusseal App for Outlook to operate normally at the send event.


Fix for Exchange Online to set OnSendAddinsEnabled to false

If you followed our original documentation you might have a policy called OWAOnSendAddinAllUserPolicy or you might have applied it to the default policy OwaMailboxPolicy-Default

The procedure to fix:
  1. connect to Exchange Online
  2. query current state of policy; the second command will indicate the OnSendAddinsEnabled property value for all policies in your tenant

  • Get-OwaMailboxPolicy -Identity OwaMailboxPolicy-Default | fl OnSend*
  • Get-OwaMailboxPolicy | fl Name,OnSend*
  • run one of these commands depending what is the name of your OwaMailboxPolicy:
    • Set-OwaMailboxPolicy -Identity OwaMailboxPolicy-Default –OnSendAddinsEnabled $false
    • Set-OWAMailboxPolicy -Identity <nameOfPolicy> –OnSendAddinsEnabled $false
  • The change can take some time to take effect, and end-users have to log out of their current OOTW session and log back in.

    Applies To
    Janusseal App for Outlook