Compress an image for email

The hard limits

Major providers cap a single message somewhere in the 20MB to 25MB range, and corporate mail servers are often stricter — 10MB is common, and some enforce 5MB. Multi-page scans and phone photos hit those ceilings easily.

When you exceed the limit the message simply fails to send, sometimes with a bounce notification hours later that the recipient never sees.

The limit that actually matters

A 20MB attachment is technically sendable and practically hostile. The recipient may be on mobile data, may be reading on a phone, and will scroll past a giant inline image without reading the message around it.

For anything meant to be viewed on screen, 200KB to 500KB is plenty — the difference is invisible at normal size. Reserve larger files for material that will be printed or examined closely.

What to do with a multi-page scan

Images compress well; a PDF containing those same images does not compress here, because this tool handles images only. If you need to send a scanned document, reduce the individual page images before assembling them into the PDF.

Privacy when emailing documents

Contracts, invoices and identity documents are exactly what people attach to email, and exactly what should not pass through an unknown compression service. Processing happens locally, so the file is only ever exposed to your own mail server — the one you already trust.