Due to antivirus and security functions implemented by many internet service providers (ISPs) and web-based email programs, you may find that the ISP or the email program thinks your script file is a virus and won't let you attach it, or else renders it unopenable on the recipient's computer. There may be other new obstacles to your emailing or receiving a Final Draft file via email as well.
The remedy is to compress the files before you attach them to the email. This puts a protective shell around the file which keeps it from being altered.
On Windows 8 / 7 / Vista / XP, right-click on the file and choose Send To > Compressed (Zipped) Folder. You will see a compressed copy of the file in the same folder as the original; attach the copy to the email.
On Mac OS X 10.10 (Yosemite) / 10.9 (Mavericks) / 10.8 (Mountain Lion) / 10.7 (Lion) / 10.6 (Snow Leopard) / 10.5 (Leopard): Control-click on the file and choose Compress "Filename."
On Mac OS X 10.4 / 3 (Tiger / Panther): Control-click on the file and choose Create Archive of "Filename."
You will see a compressed copy of the file in the same folder as the original; attach the copy to the email.
If you have earlier Windows or Mac operating systems, you should be able to find freeware or shareware file compression/decompression programs on sites such as www.nonags.com, http://www.fwnetwork.com/mac/ or www.download.com.