Goodo!

Protocol is generally that you mail a couple of times over a couple of weeks, and try any other "reasonable" way you can think of to contact them. (google for other non-stale email addresses if this is the case, etc).

If the author is persona non grata, then write to the modules@ mailing list and ask to take over the module. You will be added to the authors for the module, then patch the existing version as you see fit and upload.