PDF too large to email? Attachment limits, and five ways to send it anyway

The limits you are hitting

Every mail provider caps the size of a message, and the cap is smaller than it looks because attachments are encoded for transport, which adds roughly a third. A 20 MB PDF becomes about 27 MB on the wire. The commonly documented limits at the time of writing:

Two things make this worse in practice. The recipient’s server has its own limit, and a corporate gateway set to 10 MB will bounce a message Gmail happily sent. And a “too large” bounce can arrive hours later, after the recipient was told to expect the file. When a document matters, get it under 10 MB or use a link.

Why the PDF is bigger than it looks

A ten-page PDF that weighs 30 MB is almost always images: phone photos placed at full resolution, scanned pages stored as full-page pictures, a logo embedded once per page, screenshots pasted into a report. Text and vector drawings take almost nothing. The companion guide explains how to find out exactly what is taking the space; the short version is that the fix is nearly always about images, and that the right fix depends on where the file is going.

Fix 1: compress it, with a real number

Open Compress PDF. Bindery builds three candidates from your file on your device and prints the actual byte size of each before you pick one: Email & web resamples images to about 96 DPI, Balanced to about 150 DPI, and Print cleans the structure without touching a pixel. Image-heavy documents routinely lose 80–95%; a text-only document barely changes, and Bindery shows that instead of pretending. Scanned pages get mixed-raster treatment — a sharp text mask over a low-resolution background — which is why a scan can shrink far more than a plain JPEG recompression suggests while staying legible. Compressing twice is safe: an image is only replaced when the new version is at least 8% smaller.

For a specific number, the target pages tell you what is realistic: 5 MB, 10 MB, or the compress for email page for the mail caps above.

Fix 2: send only the pages that matter

Compression cannot remove content. If the recipient needs three pages of a forty-page scan, extract those three; the result carries only the resources those pages use and is usually a fraction of the size. If they need the whole thing but the cap is hard, split it “under a size” — Bindery cuts consecutive parts that each stay below the limit you type, measured from your actual file — and send two or three messages. Delete blank scanner pages and duplicated sheets first; they are surprisingly heavy.

Fix 3: a sealed link instead of an attachment

For anything sensitive, an attachment is the wrong channel anyway: it sits in two inboxes forever. Send securely seals the file in your browser with an AES-256 key, uploads only the ciphertext, and puts the key after the # in the link where browsers never send it. The link expires after 1, 7 or 30 days and stops after a download count you choose; Bindery’s storage cannot read the file. The recipient opens it in any browser, no account. Creating a link needs a Bindery account; opening one does not.

Fix 4: fix the source

• Scans: rescan text documents in greyscale or black-and-white at 300 DPI rather than colour at 600. Or clean the scan with Clean scanned PDF and compress on Balanced.
• Word exports: Word’s own “minimum size” PDF export downsamples images; if you still have the .docx, export again.
• Photos in a document: JPG to PDF embeds images byte-for-byte; compress the result once with Email & web.
• Slide decks: the same background image on every slide is usually the culprit; compression stores identical streams once.

Fix 5: for the truly huge

A 500 MB drawing set or a 2 GB scanned archive is not an email problem. Split it into logical parts with Split — files over 200 MB stream through Split and Extract in big-file mode on Pro without being loaded into memory — and share the parts by link. Compress each part on the Print target first if the recipient needs full quality, or Balanced if they need to read it on screen.

Which fix, in one table

Whatever you choose, keep the original. Every one of these tools writes a new file and leaves the source untouched on your device.

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