By sending private e-mails you waste everyone's time because anyone who has related questions cannot find and read the discussion and has to ask again.
Furthermore, two strategies how to reach the right person seem to be in general use when e-mailing directly: (a) write to someone and hope he will forward it to the right person (b) send the e-mail to everyone who could perhaps be the right recipient. Both waste everyone's time.
Gwyddion mailing lists are hosted on SourceForge, see SF Gwyddion mailing list page. There are two lists:
gwyddion-users intended for discussion of Gwyddion use and SPM in general. If you want to ask how to do something using Gwyddion or have troubles installing it – this is the right place. You can subscribe on the gwyddion-users SourceForge page.
gwyddion-devel intended for Gwyddion development discussion, including module development, packaging, etc. You can subscribe on gwyddion-devel SourceForge page.
Note only subscribers can post to these lists. This measure keeps the lists spam-free.
The list management software replies automatically to invalid posts (from non-subscribed addresses, with huge attachments, ...) that your post is held for approval. In fact, such posts are discarded. If your receive the automated reply please ignore it, correct the problem and then post again.
A web forum for general Gwyddion-related discussion is also hosted on SourceForge.net.
Note you need to log in to SourceForge to post.
As noted above please use the mailing list or web forum for questions and general discussion.
The official contact (whatever it means) and leader of scientific part of the project is Petr, microscopy-related questions should be directed to him. Bugs should be reported to him.
On the technical side the project is being led by David. Should you have porting, packaging, translation, and inner working of things questions, he's the right one to ask.
See also file
AUTHORS in the source code (or the list below)
for responsibilities, and areas of expertise. Authors of individual modules
can be looked up also in the module browser, either in Gwyddion as
Meta → Module list, or here on-line.
Contributors are listed in alphabetical order.