File too large to email?

If your file is too large to email, stop trying to make it fit and send a link instead. Every mainstream mail provider caps a message at 20–25 MB, and after encoding that leaves room for a file of roughly 14–18 MB. Pick a link that does not leave a readable copy of your file on someone else's server: an end-to-end encrypted peer-to-peer transfer encrypts it in your browser and streams it straight to the recipient, who needs no account to receive it.

The limits, provider by provider

These are the providers' published defaults as of October 2026, and administrators change them freely. The exact figures, and why Microsoft's own pages disagree about Outlook, are in the Gmail attachment size limit and the Outlook attachment size limit.

Why a file under the limit still bounces

Email was never designed to carry files. Attachments are encoded into the message body as text, which inflates them by roughly a third. So a 25 MB cap is not a 25 MB file cap — it is closer to 18 MB of actual file once the encoding overhead is counted.

The second surprise is that the cap is enforced twice. Your provider limits what it will send; the recipient's provider limits what it will accept. The lower of the two decides, which is why a file that leaves your outbox happily can still bounce hours later with a delivery failure notice. Corporate mail servers are frequently configured well below the public defaults.

The practical rule: under about 14 MB of file gets through almost anywhere; above 20 MB, expect trouble somewhere along the way.

The four workarounds, and what each one costs you

• Zip the file. Almost always a dead end. Photos, video, PDFs and modern Office files are already compressed, so a zip saves a few percent at best. It helps only for large collections of text, logs or raw data. See how to send a folder online if zipping is something you were doing to keep a directory together.
• Split it into parts. Technically possible, practically miserable. The recipient needs the same archiving tool, every part has to arrive intact, and one missing message ruins the set. It also does nothing for privacy — every part still sits unencrypted in two mailboxes.
• Compress the content itself. Re-encoding a video at a lower bitrate or downsampling images will genuinely shrink the file. It also destroys quality permanently, which is fine for a preview and wrong for a master, a scan or anything a professional will work from.
• Upload it and share a link. This is the workaround that actually works — and the one worth thinking about, because the choice of which link decides whether a full copy of your file now lives on a server you do not control.

Not all links are equal

When your mail app offers to upload the file to its cloud storage, or when you paste a cloud-drive share URL, you are doing the same thing: uploading the file to a provider, then sending a URL that anyone holding it can open. The file is encrypted on their disks, but the provider holds the keys, the copy stays until you remember to delete it, and the link is forwardable, loggable and indexable if it leaks.

A peer-to-peer transfer removes the copy from the equation. The file is encrypted in your browser with AES-256-GCM, streams directly to the recipient's browser, and the decryption key lives only in the URL fragment after the #, which browsers never transmit to a server. A separate PIN gates access, so an intercepted link on its own is useless. That is what zero-knowledge means in practice: the service cannot read your file even if it wanted to.

How to send the file instead

1. Sign in to SaferDrop and add the file. Up to 100 MB on the free plan, up to 2 GB on Pro — comfortably past any inbox limit.
2. Copy the link and note the PIN. The key is in the link fragment and never reaches a server.
3. Email the link, send the PIN another way. Text it, say it on the phone — the point is that one intercepted channel is not enough.
4. Keep the tab open while it streams. The transfer is direct between the two browsers, so both need to be connected.

If email is specifically the channel you have to use, read how to send files securely by email. If the file is simply big, the full method is in how to send large files securely. And for the exact numbers of the provider that turned you away, see the Gmail attachment size limit or the Outlook attachment size limit.

Frequently asked questions