壓縮用於 Email 的 PDF — 快速縮至 10MB 以下

Before compressing, know your target:

- Gmail: 25MB maximum - Outlook / Hotmail: 20MB maximum - Yahoo Mail: 25MB maximum - Corporate Exchange servers: usually 10MB, sometimes 5MB - Government / legal portals: often 1–5MB - Most iCloud Mail: 20MB

If you are emailing to a corporate address, target under 5MB to be safe. For public webmail-to-webmail, 10MB is usually fine.

1. Go to WhiskFile's Compress PDF tool and upload your file 2. Choose a compression preset: 'Balanced' for 5MB target, 'Small file' for 1MB target 3. Download the compressed PDF and check the size before sending

For most documents (reports, contracts, presentations), the 'Balanced' preset achieves 40–60% size reduction with no noticeable quality loss at typical screen reading sizes.

If your PDF is very large (50MB+) and compression alone is insufficient, consider uploading to Google Drive, Dropbox, or OneDrive and sharing the link instead of an attachment. This bypasses email size limits entirely and gives the recipient a more reliable download experience.

This is standard practice for large contracts, design files, and reports.

If you need to attach multiple PDFs, merge them first (WhiskFile's Merge PDF tool), then compress the merged file. A single compressed attachment is more professional than 10 individual files and often results in a smaller total size due to shared PDF structure overhead.