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: Limits depend on the Outlook client, sending service and recipient. Exchange Online normally defaults to 35 MB sending / 36 MB receiving, and administrators can configure limits up to 150 MB; some clients have lower limits. Body text and attachment encoding add to the message size. A cloud link avoids including the file in the message, but the file still needs to fit the cloud service’s limits and sharing policy.

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 and choose permissions that let the intended recipient access it. Use specific recipients when the file is private.
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? Exchange Online defaults to 35 MB sending / 36 MB receiving, subject to configured and client limits. Classic Outlook can impose a 20 MB default for internet-account messages; that is not a universal Gmail or Outlook.com server limit. Check the sender’s and recipient’s actual limits.

How big a file can a OneDrive link handle? OneDrive and SharePoint support individual uploads up to 250 GB, subject to available storage and other restrictions. Pasting a normal sharing link is different from Outlook’s cloud-attachment workflow, which can have its own limits; a 2 GB cloud-attachment limit does not cap all OneDrive share links.

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

Additional sources: Microsoft — Exchange Online limits · Microsoft — OneDrive file restrictions