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Add Source365 to Outlook.

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1. Download manifest.xml2. Open Outlook's Add-Ins dialog ↗

manifest.xml · ~4 KB · Office Add-in manifest

Just for you

Install in ~2 minutes when custom add-ins are allowed

  1. 1. Download the manifest file (button above).
  2. 2. Click Open Outlook's Add-Ins dialog — it takes you straight to the right place in Outlook on the web.
  3. 3. Choose My add-ins → Custom Addins → "+ Add a custom add-in" → "Add from File…" and pick the downloaded file.
  4. 4. Select Install, close the dialog, and refresh Outlook on the web.

The add-in appears in Outlook on the web AND the desktop app — they share the same add-in list. If the "Add a custom add-in" option is missing, your organization has disabled personal installs — use the team deployment instead (or forward it to IT with the button on the right).

For your whole team · recommended

One deployment, zero per-user installs

A Microsoft 365 admin deploys Source365 once — it then shows up automatically in Outlook for everyone you choose, and updates centrally. About 10 minutes, one time.

  1. 1. Open Microsoft 365 admin center → Integrated apps
  2. 2. Click "Upload custom apps" → Office Add-in → "Provide link to manifest file".
  3. 3. Paste the manifest URL, click Validate, pick users (or Everyone), Deploy.
✉ Not an admin? Email this to IT

Microsoft says centrally deployed Office add-ins can take 24–72 hours to appear. Users may also need to restart Outlook before the Source365 command is visible.

See how it works

Install in under 5 minutes

The Microsoft shortcut opens the exact Add-Ins for Outlook dialog. Add the XML file, refresh Outlook, then open the real Source365 taskpane. Personal installation depends on your organisation allowing custom add-ins.

a▍
New browser tab
Enter the Microsoft shortcut in the browser address bar above. Outlook opens after you press Enter.
Open a new browser tab and enter aka.ms/olksideload
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Requirements
  • Microsoft 365 work or school account with Exchange Online
  • Outlook desktop (Windows/Mac) with Microsoft 365 subscription
  • Custom add-ins allowed by your organisation, or admin deployment
  • Exchange On-Premises is not supported
Installation guide

Five steps, with an IT fallback.

Follow Microsoft's supported XML sideload flow. If your tenant blocks custom add-ins, use the admin deployment path above.

  1. 01

    Download the manifest file

    Click the button below to download the Source365 manifest file (.xml). This file tells Outlook where to load the add-in from, and it contains no sensitive information.

  2. 02

    Open the Add-Ins dialog

    Open https://aka.ms/olksideload in your browser. Microsoft opens Outlook on the web and loads the Add-Ins for Outlook dialog after a few seconds.

    Using the Outlook desktop app? Install via the web dialog anyway — web and desktop share the same add-in list, so it appears in both.

  3. 03

    Select "My add-ins" and upload

    In the Add-Ins for Outlook dialog, select "My add-ins" in the left sidebar. In "Custom Addins", select "+ Add a custom add-in" → "Add from File...".

  4. 04

    Select the manifest file

    Choose the manifest.xml file you downloaded in step 1. Outlook will warn you that it's a custom add-in. Click Install to proceed.

  5. 05

    Refresh Outlook and open Source365

    Close the Add-Ins dialog and refresh Outlook on the web. Open a procurement inquiry email, select Source365 from the message toolbar (or its Apps menu), then sign in with your Microsoft account.

    A free 14-day trial starts automatically after sign-in. No credit card required.

Download manifest.xmlSign in to your account
FAQ

Installation questions.

Something not working? Email our support team.

Can my IT admin deploy this to the whole organisation?
Yes — and it's the easiest path for teams. In the Microsoft 365 admin center, go to Settings → Integrated apps → Upload custom apps → Office Add-in → "Provide link to manifest file" and paste https://www.source365.io/api/manifest, then Validate and Deploy to chosen users. The add-in then appears automatically in everyone's Outlook (no per-user installation) and updates centrally. Use the "Email this to IT" button above to send your admin ready-made instructions.
Do I need admin rights to install it for myself?
Usually not. You can install the XML manifest yourself when your organisation allows custom add-ins. If My add-ins or Add a custom add-in is missing, ask an administrator to deploy Source365 through Microsoft 365 Integrated apps.
Will I lose my settings if I reinstall?
No. Your account, search history, and settings are stored in Source365's cloud, not in the add-in itself. Reinstalling or updating the manifest won't affect your data.
Does this work in Outlook on mobile?
Source365 is currently optimised for Outlook on the web and the Outlook desktop app. Mobile support is on our roadmap.
How do I update to a newer version?
Updates are delivered automatically through the taskpane, so you don't need to reinstall the manifest unless we release a new major version.
I don't see the Source365 icon after installing. What should I do?
Try opening a message (not the compose window). The add-in only activates in read mode. If it still doesn't appear, close and reopen Outlook, then check under "My add-ins" to verify the installation succeeded.

Ready to source smarter?

Install the add-in and sign in to start your free 14-day trial. No credit card required.

Download manifest.xmlView pricing