Version 1.2.0, manifest 1.2.0.0, enables SupportsSharedFolders inside DesktopFormFactor in the XML 1.1 version overrides. The earlier manifest omitted this opt-in, so Outlook could hide the add-in when a shared mailbox was opened separately. This is an activation change; the existing renderer and signature insertion code are retained.
| Outlook client | Expected coverage after manifest delivery |
|---|---|
| Mac, shared mailbox opened through delegated access | Desktop opt-in is required; verify new compose, reply and the ARK signatures command |
| Classic Windows, shared mailbox added through delegated access | Uses the add-in assigned to the employee's primary mailbox; verify compose and sender changes |
| New Windows, shared mailbox promoted or added as an account | Desktop opt-in is required for this shared context; verify with the employee's delegated access |
| Web, Open another mailbox in a separate tab/window | Desktop opt-in is required; verify compose and the command in that window |
| Android / iOS, shared mailbox | Not supported by Outlook; this release cannot enable automatic signatures there |
Use supported Microsoft 365 clients with the app's existing Mailbox 1.13 and NestedAppAuth 1.1 capabilities. See Microsoft's shared-mailbox support and setup guide and From-change behavior. These document platform support; they do not certify this app's real-client results.
Microsoft's add-in availability table, checked on 2026-09-14, explicitly covers Open another mailbox in a separate web tab/window and promoted shared mailboxes in new Windows. It requires shared-mailbox manifest support and installation in the employee's primary mailbox for compose in those contexts. These remain acceptance targets, not confirmed device results.
The selected From address controls the signature. A sender on an approved company domain that does not match the signed-in employee's primary address or directory SMTP aliases receives its Outlook display name and email, plus the common ARK/Artesian branding. If Outlook supplies no display name, the email is used. The employee's personal job title and phone numbers are omitted. New messages use the full layout; replies and forwards use the compact layout.
SSO still obtains the signed-in employee's own /me profile with User.Read. The add-in does not retrieve the shared mailbox's directory profile, phone numbers or messages through Graph. Its Office permission remains ReadWriteItem, and it writes the signature slot of the current compose item. Returning to the employee's personal From address restores their own profile details. Unapproved domains remain rejected.
The sign-in hint remains the user identity Outlook provides; it is not changed to the selected shared From address. Real shared-context SSO must be checked on each client. If authentication fails, record the support details rather than signing in directly with shared-mailbox credentials.
- Merge the reviewed PR, verify successful Pages publication and check that the hosted manifest is 1.2.0.0.
- In Microsoft 365 Settings → Integrated apps → ARK signatures, update the existing app's manifest from
https://arklab.github.io/manifest.xml(or upload that downloaded file). Keep the existing app ID and employee assignment list. - Keep the add-in assigned to employees' primary mailboxes. Microsoft advises against assigning it directly to shared mailboxes. Existing Exchange delegation and Send As/Send on Behalf permissions remain separate and are not altered by this update.
- Verify the saved update, allow Microsoft's delivery delay and restart Outlook before creating a new draft from the separately opened shared mailbox. Pages publication alone cannot update the manifest stored in Microsoft 365.
On Mac and the Windows variant used by the employee, open a shared mailbox separately using delegated access. Also test web Open another mailbox if used by the team. Keep mailbox addresses, screenshots and assignment evidence in internal records.
| Check | Status |
|---|---|
| Desktop opt-in in generated XML, retained desktop events/commands and mobile declaration | Automated checks pass |
| Microsoft XML manifest validation | Passed for 1.2.0.0 |
| Full/compact shared-sender output, compose preview and switching back to the employee | Simulated checks pass; no borrowed title or phone |
| Microsoft 365 manifest 1.2.0.0 delivered | Pending |
| ARK signatures command visible in the separately opened shared mailbox | Pending |
| Silent SSO and automatic signature in a fresh shared-mailbox draft | Pending |
| Reply/forward, repeated manual refresh, switch between personal/shared From | Pending |
| Received message retains mailbox identity, links and branding | Pending |
| Existing personal-mailbox desktop and Android signatures still work | Real-client regression pending |
If the command remains absent after delivery, verify the actual client, mailbox-opening method and employee assignment. Microsoft also documents a limitation for mailboxes hidden from address lists: the current item may be unavailable to the add-in. Diagnose that separately; do not automatically change mailbox visibility or grant broader permissions.
For shared-mailbox messages on mobile, use a manually entered signature until a separately approved mobile-compatible approach is adopted. This release does not introduce a server-side signature service.