FileKitHow to Compress a PDF for Email — Stay Under the Attachment Limit
How to shrink a PDF to fit within Gmail, Outlook, and corporate email attachment limits. Covers compression, page removal, splitting, and best practices.
Email Attachment Limits You Need to Know
Most email providers cap attachments at a specific size. Gmail allows 25 MB, Outlook 20 MB, and Yahoo 25 MB — but corporate Exchange servers often set tighter limits at 10 MB or even 5 MB. When your PDF exceeds the limit, the email bounces silently or lands in the spam folder.
| Provider | Attachment Limit |
|---|---|
| Gmail | 25 MB |
| Outlook / Office 365 | 20 MB |
| Yahoo Mail | 25 MB |
| Corporate Exchange | 5-10 MB (varies) |
| iCloud Mail | 20 MB |
Quick Method: Browser Compression
The fastest way to shrink a PDF for email is to use FileKit PDF Compressor. It runs entirely in your browser, so your document stays private — especially important for contracts, invoices, or HR files.
- Open the compressor and drop your PDF
- Select Balanced for most documents, or Strong if size is critical
- Download the compressed version and attach it to your email
This typically reduces files by 40-70%, bringing a 15 MB report down to 4-6 MB comfortably within most email limits.
When Compression Alone Is Not Enough
If your PDF is image-heavy (presentations, photo portfolios, scanned contracts), compression may only get you partway. Additional strategies:
- Remove unnecessary pages. Use PDF Page Remover to strip cover pages, blank pages, or appendices the recipient does not need.
- Split into parts. Use PDF Splitter to send the document across two emails with a note like “Part 1 of 2.”
- Convert images to lower resolution. If you have the source file (Word, Slides), re-export at 150 DPI instead of 300 DPI.
Best Practices for Email Attachments
- Compress before signing. Digital signatures are invalidated by re-compression. Always compress first, then sign.
- Flatten forms. If the PDF has form fields or annotations, use PDF Flatten to reduce overhead.
- Name the file clearly. Rename to something descriptive like “Invoice-2025-03.pdf” rather than “scan001.pdf” to avoid spam filters.
- Test first. Send the email to yourself before sending to the recipient to verify the attachment is intact and readable.
Alternatives to Email Attachments
When a PDF is genuinely too large for email even after compression, consider:
- Cloud sharing (Google Drive, Dropbox, OneDrive) with a link in the email
- Secure file transfer services for sensitive documents
- Compressing images before creating the PDF in the first place