"The file is too large to attach." If you've seen that message, your PDF is over your email provider's limit — typically 25 MB for Gmail and 20 MB for Outlook. The fix is to compress the PDF, and you can do it free in a few seconds.
You'll see the before-and-after size instantly, so you know it's now small enough to attach. Everything happens in your browser, so the file is never uploaded anywhere.
Almost always, it's images. PDFs created from a scanner or full of photos store high-resolution images that are far larger than they need to be for email. Compression re-optimises those images, which is where the big savings come from — scanned documents often drop by 40–70%.
If you need it under 25 MB for Gmail, Recommended is usually enough. To squeeze under a tighter limit (say 10 MB or "under 100 KB" for a web form), use Strong. If it's still too large, you can also split the PDF and send just the pages that matter.
If a document simply won't shrink enough — for example a huge high-quality scan you can't degrade — upload it to a cloud drive and email the link instead. But for the vast majority of everyday PDFs, compressing is faster and keeps everything in one attachment.
Yes. At the Recommended level most people can't tell the difference on screen. Keep your original file as the master copy, and send the compressed version. Once it's small enough, attach it in Gmail or Outlook as normal and hit send.