Send a Large Attachment in Outlook (Size Limits and OneDrive Links)

When Outlook rejects an attachment as too big, the fix is usually to send a cloud link instead of the file itself.

Why: Mail servers cap message size. Microsoft 365/Exchange business accounts default to a 10 MB total limit, and internet accounts like Outlook.com or Gmail to about 20 MB — and that ceiling counts the attachment and the message body together. A OneDrive link sidesteps the cap entirely.

Fix 1: Share a OneDrive (or other cloud) link instead of attaching

This is the recommended route for anything large:

1. Upload your file to OneDrive (or Dropbox, Google Drive, iCloud).
2. Get a sharing link from that service.
3. Paste the link into your email. The recipient clicks it to download — your message stays tiny and the link doesn’t count toward the size limit.

Sharing a link also lets recipients open the latest version and collaborate, rather than passing copies around.

Fix 2: Resize large images before sending

If the bulk is photos:

1. Attach the images to your message.
2. Go to File → Info.
3. Under Image Attachments, select Resize large images when I send this message.
4. Return to the message and select Send. Outlook shrinks the images on the way out.

For pictures pasted into the body, select one, then on the Picture Format tab choose Compress Pictures and pick a lower resolution such as Web (150 ppi).

Fix 3: Zip the files

For documents and mixed files, compress them first: in File Explorer, select the files, right-click → Compress to ZIP file (or Send to → Compressed (zipped) folder on older Windows), then attach the single, smaller .zip. If the zip is still over the limit, fall back to Fix 1.

FAQ

What’s the actual limit? Roughly 10 MB on Microsoft 365/Exchange business accounts and 20 MB on internet accounts (Outlook.com, Gmail) — and your admin or provider can set it lower.

How big a file can a OneDrive link handle? Far more than email — OneDrive supports files up to 2 GB, and the link itself adds almost nothing to the message size.

I still get “attachment size exceeds the allowable limit.” The total message is over the cap. Remove the file and send a link instead (Fix 1), or split it into smaller attachments.

Sources: Microsoft Support — Reduce attachment size to send large files with Outlook