Are you unable to send a PDF file quickly because it is too large? Large files are always a headache, whether through email or instant messaging tools. This article details how to use online tools to compress PDF files for quick sending. Determining PDF File Size Limits First, you need to determine the file recipient's specific file size limits. Most email services allow attachment sizes under 25MB, while instant messaging tools such as WeChat and QQ are typically limited to 50MB. If your PD…