Start with your target size based on the recipient mail service attachment limit.
2
Compression Order
Compress in steps: begin at medium level, check readability, then reduce further only if needed.
3
By Document Type
Text-heavy PDFs are usually optimized with minimal visible loss, while image-heavy PDFs need resolution tuning.
4
Versioning
Use consistent naming and versioning in both filename and email body.
5
Mobile Validation
Always test openability on mobile before sending to clients.
6
Team Standard
If this is recurring work, standardize one default compression level across your team.