Email is a pretty good way to send short text messages, but it's not great at sending files. The basic protocols are pretty simple and we've got a lot of experience using them. I can see the appeal of email.

There's no way that outlook is the best tool for the job though, and it's no surprise at all that they're having problems with it. It's a complete mess with insane amounts of overhead and bloat if all you want to do is send text. Even the message headers it sends/mangles are trash. It's a pain to work with on the end user side too. I can't imagine that they couldn't have written a basic email client that would do the job better with far fewer problems/resources or used/built off of any number of decades old open source projects.

This comment is downvoted, but it is correct. Emailing a file takes roughly 30% more bandwidth than a file transfer protocol (any such protocol, not necessarily FTP) due to mime encoding.