Behind the cards, images are resampled to 150 DPI (Balanced) or 96 DPI (Email & web) and re-encoded only when the result is genuinely smaller; duplicate streams are stored once; text is left as text. The attachment you are compressing is often the sensitive part of the email — a contract, a statement, medical paperwork — and it never leaves your browser to be compressed. If the recipient needs the original quality, send the compressed copy by email and the full-resolution version another way, or split the document under a size and send the parts as separate messages.
How it works
- Drop the PDF and open Compress
- Pick the level that lands under your mail server’s cap — 10 MB is a safe default
- Download and attach; keep the original for the recipient who needs full quality
Questions people ask
What attachment size should I aim for?
Gmail allows 25 MB and Outlook.com 20 MB per message, but the recipient’s server has its own limit, often 10 MB, and the whole message including encoding overhead has to fit. Under 10 MB works almost everywhere; under 5 MB opens quickly on a phone.
Will the person receiving it notice the compression?
At Balanced, not at normal zoom: images stay at 150 DPI, text is untouched, and links and bookmarks are carried over. At Email & web, photographs and scans look softer when zoomed or printed — it is a screen-reading setting, which is what most email attachments are.
What if compression cannot get the file small enough?
Split under a size breaks the document into parts that each stay below your cap, measured by actually writing each part, so you can send them as separate emails. Or, with an account, Secure handoff creates an end-to-end encrypted link that expires and stops after a set number of downloads.