PDFs are usually read-only, but they can still be modified if the recipient has specific editing software, so when you send or share a PDF document, you might want to protect it from that or even ask for a password before opening the file. How to do it?
If you’ve ever dealt with trying to send a large file via email, you know how frustrating it can be. Many email servers flat out refuse to accept email attachments of a certain size. To help save you time and hassle, try compressing your PDF file before you send it.