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.
Protocol is generally that you mail a couple of times over a couple of weeks, and ...
Yup. I know what the protocol is - just not had the tuits available to implement it :-)
Although, a maintainer recently popped up on the T::U mailing list who looks like they might be considering making some changes - so I may not need to bother.