Sending files can sometimes be a bit pesky. Depending on the size limit set by your SMTP server, you will usually end up splitting the file in smaller chunks or following
some other method. There are various compression mechanisms out there that work OK, such as zip or rar. Lately, I have found a new compression format called 7z.
I have been compressing archives and the level of compression of 7z (especially with word files that have embedded images) is amazing. I was able to compress a 24 Mb word file to 4 MB in less than 5 seconds. I really don't know if RAR offers the same (or better) compression ratio, but AFAIK, there is no RAR compression solution for OS X.
7z has various clients available for lots of platforms out there. My personal for OS X is
7zX. Download one of them and give them a try, you might save a byte or two.