I am encountering what appears to be a bug or tenant‑specific issue with the Office 365 Outlook – Send an email (V2) action in Power Automate when using the single “Attachments” array field.
Summary:
Sending an email with one attachment using Attachment Name / Attachment Content fields works correctly.
Sending an email with multiple attachments using the Attachments array field results in corrupted / unreadable files, even when the array is hard‑coded with known‑good base64 content.
If possible, I would appreciate confirmation and guidance on whether this behavior is expected or scheduled to be addressed.
Details
Action:
Office 365 Outlook → Send an email (V2)
(and Send an email from shared mailbox (V2))
Expected behavior:
When providing an array of attachment objects in the Attachments field, each attachment should arrive intact and be openable.
Actual behavior:
- The email sends successfully.
- Attachments arrive but are corrupted (Word/PDF cannot open them).
- This occurs even when the attachments array is hard‑coded with valid base64 strings that are known to open correctly when used elsewhere.
What I have verified:
- Base64 strings are valid (they open correctly when used in other tools / contexts)
- ✅ Array structure is correct:
[
{ "Name": "test.pdf", "ContentBytes": "<valid base64>" },
{ "Name": "test.docx", "ContentBytes": "<valid base64>" }
]
- ✅ No data URI prefixes (data:application/...)
- ✅ No line breaks in base64
- ✅ File sizes are small (KBs, not MBs)
- ✅ Same behavior occurs with:
- Runtime‑built arrays
- Hard‑coded arrays
- ✅ Single attachment fields work
- ❌ Attachments array field always produces corrupted files
Impact:
This makes it impossible to send a single email with multiple attachments using the Outlook connector in this environment, unless:
- Multiple emails are sent, or
- Links are used instead of attachments, or
- Graph API / HTTP is used (not allowed by company policy)
Questions:
Is this:
- A known bug with the Outlook connector?
- A tenant / rollout ring issue?
- A documented limitation of the Attachments array field?
If possible, I would appreciate confirmation and guidance on whether this behavior is expected or scheduled to be addressed.
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