n8n Outlook “Create draft” fails with an attachment

What's going on

The node sends the draft and its attachment in a request Microsoft Graph won't accept. It has been reported since late 2025 (n8n#23132, community thread) and was closed without a fix.

Workaround: build the draft with HTTP Request nodes

1. Create the draft without the attachment: POST https://graph.microsoft.com/v1.0/me/messages with the subject, body and recipients. Keep the id it returns.
2. Add each file under 3 MB: POST /me/messages/{id}/attachments with "@odata.type": "#microsoft.graph.fileAttachment", a name and the file as base64 in contentBytes.
3. Files of 3 MB or more: call POST /me/messages/{id}/attachments/createUploadSession, then upload the file in chunks to the URL it returns.
4. Inline photos: add the image as an attachment with "isInline": true and a contentId, and show it in the body with <img src="cid:yourContentId">.

Use your Microsoft OAuth2 credential on the HTTP Request nodes, with the Mail.ReadWrite scope.

Using n8n to give Claude Outlook drafts?

If the flow exists so Claude can prepare Outlook drafts, Draftbee replaces it with one connector. Templates live in your Outlook “Templates” folder, and attachments, large files, inline photos and signatures are handled for you. Keep n8n for everything else. Compare the two.

Set it up in five minutes

1. Sign in with Microsoft at https://app.draftbee.app. Your 14-day free trial starts, no card needed.
2. In Claude, open Settings → Connectors → Add custom connector, name it Draftbee and paste https://app.draftbee.app/mcp.
3. Put an email you send often into an Outlook folder called “Templates”, with blanks like [Client name].
4. Ask Claude: “Use my viewing follow-up template for Sarah at 14 Elm Road and attach the brochure.” The draft appears in Outlook, ready for you to check and send.