The size limits you're up against
Gmail caps attachments at 25 MB. Outlook.com and Microsoft 365 cap at 20-150 MB depending on plan. Yahoo Mail caps at 25 MB. Most corporate Exchange servers cap at 10-25 MB before bouncing.
Even when your provider accepts a larger file, the recipient's gateway might reject it. The safe target for a PDF you're sending cold is under 10 MB.
Method 1 — compress first (works 80% of the time)
Run the file through Compress PDF on the Recommended preset. Image-heavy PDFs typically shrink 60-80%, which brings most over-the-limit files comfortably under any cap.
If Recommended isn't enough, try High — for screen viewing the difference is rarely visible. Don't bother with Low for email; it barely shrinks anything.
Method 2 — split into chunks
If compression alone won't get you there (e.g. a 200 MB scanned book), split the PDF into 50-page chunks and email them separately. Use Split PDF with the 'every N pages' option.
Number the parts in the filename (Report_part_1_of_4.pdf) so the recipient can reassemble them with Merge PDF on their end.
Method 3 — share via cloud link
Upload to Google Drive, Dropbox, or OneDrive and share a link. The recipient downloads on their schedule, you don't fight attachment limits, and you can revoke access if you sent to the wrong address.
For sensitive documents, set the link to require sign-in (Drive's 'Anyone with the link' is convenient but riskier). Or password-protect the PDF first with Protect PDF, then share the link freely.
Method 4 — Gmail's built-in Drive integration
If you're on Gmail and the file is over 25 MB, Gmail prompts you to share via Drive automatically. The recipient gets a clickable preview without leaving their inbox.
Outlook offers the same integration with OneDrive. Use it — it's the friction-free version of Method 3.
Method 5 — large-file transfer services
WeTransfer, Smash, and similar services let you upload up to 2 GB and email a download link. Free tiers have ads and short link lifetimes; paid tiers are cleaner.
Avoid using these for highly sensitive content unless you've vetted the provider's privacy practices. A cloud-storage link from a major provider is usually a safer default.
What to avoid
Don't ZIP the PDF to 'compress' it — PDFs are already compressed internally, and ZIP gains 1-2% at most while breaking inline previews.
Don't print to PDF at lower DPI hoping for a smaller file — you lose searchable text. Use a real PDF compressor instead.
Don't email password and PDF in the same message. Send the password by a different channel (SMS, Signal, in person).