Not being able to attach a file to an email is frustrating. If you're unable to attach a file, there are a few things to check.

File is too large - each email can contain no more than 25MB in total
Special characters - remove special characters from the title and try again
Unsupported web browser - make sure you’re using a supported web browser
Email containing files that can be a security risk won't be delivered - we don't support a variety of file formats, such as .exe, .bat, and .jar, because they can be used to distribute malware