Peter is right—the only way to do this is as MusicXML.
The menus are different between 2011 and 25. In 25, you will find MusicXML under File / Export. Easy...
In 2011, under the File menu, go to MusicXML and select Import and then find the file to begin. There will be a lot of errors due to changes in the XML spec over the last six years. Your boss must click through each one but the file should open eventually. Any features not supported by 2011 or MusicXML 3.0 will not appear on the page. My 2-page test file did open just now after clicking through 13 errors.
You don't say how you send the files to your boss. If there are permissions or privileges issues on his/her end, zip your file before uploading it to a server/Dropbox/direct transfer/sneakernet etc. Un-zipping automatically grants those permissions as long as the file isn't locked. If the file opens on the other machine without zipping, then that is not a problem of course. Email will zip/unzip attached files automatically—no problem there.