I don't know who these users are, why they are sending you code or what your role is, but let's assume the users are developers and your job involves applying patches to controlled environments that they don't have access to themselves.
Ideally they should send a link to the source code in svn, git or whatever you use, together with a version number (or else you could make a note of the version, or the developers could use version tags to embed the version information within the source code as a header comment). Whatever your deployment system, it should be possible to find out later exactly what was deployed.
Then you could open this file (or copy & paste if you really have to I suppose) into a Program window, which provides a full-featured code editor complete with a navigator panel and detailed compilation errors.