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📎 Attachment support in Outlook add-ins

Our add-in uses the Outlook JavaScript API to fetch email attachments and create email documents. These features are supported in Read mode (when you open an existing email), but only in Outlook clients that expose attachment identifiers to the add-in.

✉️ What are Read mode and Compose mode?

  • Read mode

  • This is when you open an existing email (one you received, or one you sent and are viewing in your Sent Items).

  • In this mode, the email already exists in the mailbox, and attachments have unique IDs.

  • → Our add-in can fetch attachments here (if the Outlook client supports it).

  • Compose mode

  • This is when you are writing a new message (New Email) or replying/forwarding an existing one.

  • The email is not yet saved in the mailbox, and attachment IDs are not assigned.
  • → Outlook does not expose attachment IDs here, so our add-in cannot fetch attachment content in Compose mode.

✅ Where attachment fetching works

  • Outlook on the web (OWA) – supported in Read mode.
  • New Outlook for Windows – supported in Read mode.
  • Outlook for Mac (subscription builds, v16.24 or later) – supported in Read mode.
  • Outlook for Windows (subscription builds, version 1901 or later) – supported in Read mode.

⚠️ Where it does not work

  • Classic Outlook for Windows (the older IE-based add-in host) — attachment IDs are often missing, even in Read mode.
  • Outlook for Windows MSI/perpetual editions (2016/2019/2021) — stuck on old API sets, attachment fetching not supported.
  • Compose mode in any Outlook client — attachment IDs are never exposed here.

📱 Outlook mobile (iOS & Android)

  • Add-ins are supported in Read mode only.
  • Fetching attachment content is not supported on mobile.
  • Email document creation (.eml files) is not supported on mobile devices due to the inability to fetch inline images and attachments that may be embedded in emails.

📧 Email Document Creation (.eml files)

Email document creation allows you to save a complete copy of the email as an .eml file for archiving purposes. This feature has the same limitations as attachment fetching since it requires access to inline images and embedded content.

✅ Where email document creation works

  • Outlook on the web (OWA) – supported in Read mode.
  • New Outlook for Windows – supported in Read mode.
  • Outlook for Mac (subscription builds, v16.24 or later) – supported in Read mode.
  • Outlook for Windows (subscription builds, version 1901 or later) – supported in Read mode.

⚠️ Where email document creation does not work

  • Outlook mobile (iOS & Android) – not supported due to Office.js API limitations.
  • Classic Outlook for Windows – limited support due to API restrictions.
  • Outlook for Windows MSI/perpetual editions – not supported.
  • Compose mode in any Outlook client – emails haven't been sent yet, so document creation isn't applicable.

💡 Workarounds

  • If you need attachment support or email document creation, use New Outlook for Windows or Outlook on the web.
  • In Classic Outlook or Compose mode, you can still save attachments manually and upload them to Lime CRM.
  • On mobile devices, email content is still saved as notes in Lime CRM, but without the complete .eml document.