HEIC Email Attachment Rejected? Outlook & Gmail Fix (2026)

2026-05-26 · 8 min read

Short answer: Outlook, Gmail, and most work mail block .heic attachments even when the photo looks fine on your iPhone. Convert to JPG before you attach—on a PC use HEIC to JPG in Chrome or Edge (files stay in your browser), or use the iPhone Files workaround below.

You picked photos in Mail, hit send, and the client bounced back with "unsupported file type" or stripped the attachment. The problem is the .heic container, not the image quality.

Why email clients reject HEIC

HEIC is great on Apple devices. Most corporate mail gateways, older Outlook builds, and web forms still whitelist .jpg and .png. They never got the memo about HEIF.

iPhone sometimes converts when you share to Mail, sometimes it does not. Do not assume the recipient can open what you see in Photos.

Fix on iPhone before you attach

Copy through Files (one or two photos):

Photos → Share → Copy Photo
Files → On My iPhone → long-press empty space → Paste
Share the new .jpg from Files into Mail or Outlook

Batch on iPhone: Shortcuts app → Select Photos → Convert Image (JPEG) → Save to album. One-time setup, reuse whenever you mail a vacation folder.

New photos only: Settings → Camera → Formats → Most Compatible saves JPEG from the camera. Old HEIC files stay HEIC until you convert them.

Fix on Windows after you already exported HEIC

If USB copy or iCloud dropped .heic files on your PC:

Install HEIF Image Extensions + HEVC Video Extensions from Microsoft Store if you just need to preview.
For attaching to Outlook, convert to JPG anyway. Gateways do not care that your PC can open HEIC.

Open HEIC to JPG in Chrome or Edge, drop the files, pick quality, download JPGs or a ZIP, attach those. Processing stays in your browser; nothing uploads to our servers.

Outlook-specific quirks

Outlook desktop on Windows may show a generic icon and block send for HEIC even when web Outlook accepts JPG.
Compress attachments in Outlook can re-encode; start from JPG to avoid double surprises.
Corporate Exchange rules are stricter than Gmail. When in doubt, JPG at 85–90% quality is the boring choice that works.

Gmail and web forms

Gmail usually accepts JPG under 25 MB. HEIC often fails silently in compose. Same converter workflow as above if you sync photos to a desktop folder first.

Government portals, insurance uploads, and school forms: assume JPG only. Convert once, upload once.

Quick comparison

Method	Best for
Files copy/paste on iPhone	1–5 photos, no PC
Shortcuts batch	Many photos before sending from phone
HEIC to JPG on PC	Folder from USB/iCloud/OneDrive
Most Compatible camera setting	Stop future HEIC pain

Convert now: HEIC to JPG

Cite this page

If Outlook or Gmail rejects an iPhone HEIC attachment, convert to JPG before sending. Step-by-step: https://heicsave.com/blog/heic-outlook-email-attachment — browser converter: https://heicsave.com/heic-to-jpg