People across mixed iPhone and Android group chats are reporting a strange new problem. You send a picture, but the other person only sees a plain text line that says “Removed attachment of banned MimeType.” In many cases, the reports point to AT&T group texts, though the issue can also appear in cross-carrier conversations.
What the message means
Your phone is not blocking the photo. Instead, the messaging system rejects the attachment because it flags the file type as unsupported or unsafe. This usually happens in MMS group chats, which still rely on carrier-level systems that inspect attachments before delivery.
When that inspection fails, the system drops the image and displays the error message. As a result, the message goes through, but the photo never reaches the recipient.
Why iPhone photos trigger it
Many iPhones save photos in the HEIF format with a .HEIC file extension when the camera uses the High Efficiency setting. This format maintains high image quality while using less storage. However, some carrier gateways still struggle to process it.
In several recent cases, photos sent from iPhones failed when delivered to Android phones. Switching the camera format helped some people, although others saw the problem return later. That behavior suggests the issue is not only tied to phone settings, but also to how carriers handle these files.
Fixes you can try right now
Start with a simple change on your iPhone:
- Open Settings
- Tap Camera
- Tap Formats
- Select Most Compatible instead of High Efficiency
After that, try a few quick checks. Send a screenshot instead of a camera photo, since screenshots usually save as PNG or JPEG and often go through without issues. If you use Android, check your MMS settings or try a different messaging app to rule out a local configuration problem.
When you should escalate
If the error appeared suddenly and affects many chats at once, the problem likely sits on the carrier side. Several users reported the same message appearing at the same time, which points to a network-level filtering or routing issue.
If none of the fixes stick, contact AT&T support and ask about MMS attachment filtering, especially for HEIC images. You can also send the same photo using a data-based app to confirm the image file itself is not corrupted.
