Why email rejects your PDF
Every provider sets a hard limit on attachment size. Go over it and the message won't send — usually with "Attachment too large" or "message size exceeds the limit". The thresholds:
| Email provider | Attachment limit | Safe target for a PDF |
|---|---|---|
| Gmail | 25 MB | ≤ 18 MB |
| Outlook / Microsoft 365 | 20 MB | ≤ 15 MB |
| iCloud Mail | 20 MB | ≤ 15 MB |
| Yahoo Mail | 25 MB | ≤ 18 MB |
| Most corporate servers | 10–15 MB | ≤ 8 MB |
The "safe target" is lower than the stated cap because attachments are MIME-encoded in transit, which inflates them by roughly 33%. A 25 MB file travels as about 33 MB. Compress below the safe target and the message gets through.
What actually makes a PDF big
Text-only PDFs are usually tiny. The heavyweights are scanned documents and image-heavy files — a scanned contract, a photo brochure, a report full of screenshots. The Unfuss PDF compressor re-renders those pages at a lighter resolution, which is exactly where the big savings come from. It runs in your browser, so the file is never uploaded.
Step by step
- Open the PDF compressor. It loads, then runs entirely on your device.
- Drop your PDF onto the drop zone.
- Pick a level — start with Balanced. If the result is still over your limit, try Strong.
- Check the new size shown next to the result, then download the smaller PDF.
- Attach the compressed file to your email instead of the original.
If it's still too big
Two options. Send fewer pages: use Split PDF or Extract Pages to pull out just what the recipient needs, then compress that. Or skip the attachment entirely: upload to Google Drive, Dropbox, OneDrive, or WeTransfer and paste the share link into your email — that works for any size.
Frequently asked
What is the maximum PDF size I can email?
Gmail and Yahoo cap at 25 MB, Outlook and iCloud Mail at 20 MB. Many corporate servers cap lower. Because email encoding inflates files by about a third, aim for under 18 MB for Gmail and under 15 MB for Outlook.
Is the PDF uploaded when I compress it?
No. The compressor runs entirely in your browser, so your PDF never leaves your device — which matters for contracts, statements, and other private documents.
My PDF is mostly text and won't shrink much — why?
Text PDFs are already small. This compressor shrinks image-heavy and scanned PDFs the most. If a text PDF is still too big, split out only the pages you need to send.
What if it's still too large after compressing?
Split the PDF and send only the pages you need, or upload to Google Drive, Dropbox, or WeTransfer and paste a share link into the email instead of attaching the file.