Email attachments
- Maximum file size
- 25 MB
Source: Unable to attach files in Outlook.com ↗ · checked 21 October 2026
Outlook.com: attachment too large?
Drop your file here. Refentra checks it against the Outlook.com email limit and makes a smaller copy without uploading it anywhere.
Choose the destination
Rule: Outlook.com · Email attachments
View the ruleRule: Outlook.com
Why Outlook.com rejects the file
- The limit covers the whole email. 25 MB includes the text, inserted pictures and all attachments.
- Resizing a picture in the email doesn't shrink it. Microsoft points out that resizing an image doesn't reduce its file size. The original bytes are still sent.
- Work accounts follow other rules. Microsoft 365 and Exchange mailboxes can have different limits; this page covers Outlook.com.
How to make it fit
- Drop the file and read the size check.
- Choose "Make it fit" to compress the image or PDF itself.
- Attach the new copy instead of the original.
Pitfalls
- Inserting a photo into the message body counts just like attaching it.
- Several attachments add up. Shrink the largest files first.
Questions
Why does Outlook still say the email is too large after I resized the picture?
Dragging the picture smaller only changes how it is displayed. Compress the file itself and attach it again.
Does this work for PDFs?
Yes. Scanned PDFs usually shrink the most because their pages are images.