Comment 2 for bug 1203359

While the built-in archivers do currently return None, it is possible that more information can be provided about the archived message. That's why the interface leaves it open to return the archive url if available.

It's possible MHonArc could be made to do this; contributions welcome.

It's possible the prototype archiver could do this as well. Happy to take a contribution for this too.

For now, the interface is right, but the existing IArchiver implementations should be explicit in their return of None. We don't want to rely on Python's implicit return of None. I'll make that fix.