Most email providers cap attachments around 25 MB, and a scanned document, a report full of images, or a long combined PDF can blow past that easily. Compression solves this most of the time — but not always, and it’s worth knowing what to do when it doesn’t.
Compress PDF is the right first step for almost any oversized file — it targets the images inside the document, which are nearly always what’s driving the size, while leaving text sharp. The full breakdown of what makes a PDF large in the first place is in How to Compress a PDF for Email.
Compression alone doesn’t always clear the limit, though. A very long scanned document adds up regardless of how well each page compresses individually. Content that’s already been compressed once — a file re-saved or re-exported multiple times — sometimes has little size left to give up without becoming illegible. And a hard limit well under 25 MB is still enforced by some portals and older email systems. PDF Still Too Big After Compressing? goes into why a particular file refuses to shrink, which is worth reading before you assume compression has failed.
When that happens, split it instead of shrinking it further. Split PDF breaks a file into smaller parts — by page range or into individual files — that you send as multiple emails or attachments instead of forcing one file under the limit. This is often a better outcome than compressing further, since it keeps every page fully legible rather than trading quality for size. How to Split a PDF Into Separate Files covers the split modes, and Split a PDF Under a File Size Limit covers picking the split points when a specific cap is the target.
It’s also worth asking whether the recipient needs the whole thing. Not every recipient needs every page — if only a specific section is relevant, extract just those pages rather than sending, and having them wade through, the full document. This is frequently the fastest fix of all, and it produces a smaller, more useful file than any amount of compression would. When it’s one page rather than a section, there’s a shortcut: in Edit PDF, every page thumbnail has its own extract button that saves just that page as its own PDF. One page out of a hundred-page report is going to clear any attachment limit, and the recipient gets exactly what they asked for.
If splitting still isn’t practical — say, the file genuinely needs to stay as one document — What Is the Best File Format for Emailing a Document? covers the trade-offs between formats, including when a shared link to a file is more appropriate than an attachment at all.
Try Compress PDF first, then Split PDF if it’s still too big — both free, no sign-up, and files wiped the moment each download finishes.