Why Your Email Attachments Won’t Open (Fixing HEIC in Outlook & Gmail)
Updated: January 2026
It happens every day in offices across the world: A client or colleague sends you a few photos of a project. You see the paperclip icon in Outlook or Gmail, but when you click to preview the image… nothing happens.
Or worse, you download the file to your desktop, double-click it, and Windows asks you: “How do you want to open this file?”
The file isn’t broken. It’s just an iPhone photo disguised as an incompatible .HEIC file. In this guide, we will show you how to view these attachments instantly and how to send photos that actually work for your recipients.
The “Preview” Problem
Modern email services like Gmail and Outlook are great at showing you a “Preview” of your attachments so you don’t have to download them. However, their preview engines are often based on older web standards.
- Outlook (Desktop): Relies on your computer’s operating system. If your Windows PC can’t read HEIC, Outlook can’t either. (See: How to Fix Windows 10/11 HEIC Issues).
- Gmail (Web): Often displays HEIC files as a generic “Mountain” icon instead of the actual photo, forcing you to download it blindly.
I Received an HEIC File. How Do I View It?
If you are staring at an attachment you can’t open, don’t email the sender back asking for a new file (that takes too long). Just convert it yourself.
- Download the attachment to your computer.
- Drag the file into the tool on our Home Page.
- Click “Download” to get the JPG version.
- Now you can open, view, and print it anywhere.
Sending Photos? Don’t Be “That Person”
If you are the one sending photos from your iPhone to a business associate, you are causing them this headache.
To look professional, you should always ensure your attachments are universal JPGs.
If you are sending from your Computer:
If you AirDropped photos to your Mac or copied them to your PC, they might still be HEIC. Run them through our Batch Converter first. It takes seconds and ensures your recipient can actually see your work.
If you are sending from your Phone:
The iPhone Mail app usually converts them automatically, but if you select “Actual Size,” it might force the HEIC format. To prevent this forever, read our guide on Changing iPhone Camera Settings to JPG.
Why Android Users Hate Your Emails
If you email a photo to a friend on an Android device, they might see a “black box” or a broken link.
Android phones vary wildly in what they support. While some newer Samsungs can open HEIC, many budget Androids cannot. Using JPG ensures 100% compatibility.
Help your friend: Send them our article on How to Open iPhone Photos on Android.
Trying to Paste into an Email Body?
Instead of attaching a file, maybe you are trying to paste the image directly into the text of the email (Inline Image).
Outlook and Gmail frequently fail to render pasted HEIC data. The image often turns into a small red “X”. Always convert to JPG before pasting into an email body or a Word document.
Learn more: Fixing Image Errors in Word & PowerPoint.
Email Attachment FAQ
Why does the file size change when I email a photo?
HEIC files are very small (high compression). When you convert them to JPG, they might get slightly larger. However, JPGs are universally accepted. If you need to send many large photos, we recommend Zipping them first.
Can I change the file extension from .heic to .jpg manually?
NO! This is a common myth. If you just rename the file photo.heic to photo.jpg, you will corrupt the file and it will not open. You must perform a mathematical conversion using a tool like HEICtoJPGFast.
Is it safe to upload confidential work attachments to your converter?
Yes. Unlike other sites, we use Client-Side Processing. Your confidential work documents never leave your computer. We do not see them, store them, or email them.