You may know what you are doing; but Microsoft knows it better...

Even if you are genius and you know exactly what you should do - Microsoft
knows that better for you. This is the reason why programmers don't like
Microsoft. You cant send over email .vb file because it will be permanently
blocked in a way you have either to dig system registers or to manually
extract content of .eml.

http://office.microsoft.com/en-us/outlook-help/attachment-file-types-blo...

There is even no option of allowing disabled files even for advanced users....
Remember: you are dumb! and you shouldn't do that; no matter who you really are.