On a PC: Open Files Explorer. When your email provider says no to that large file, Smash always Follow these easy steps to compress a large PDF file online: Click the Select a file button above, or drag and drop files into the drop zone. Select “Get Info.” Look at “File Size” to see how large the PDF is. Most email services limit the size of an attachment toMB. On a Mac: Open Finder. Key Takeaways. Send large files by using file sharing, cloud services, or other solutions for working around fil