I wanted to contact off list a member of my group.
As a moderator or owner of the group you can send a message to the member through the Members list.
o? Find the member(s) in the list
o? Click the checkbox on the (each) member's row
o? In the Actions menu, select Send Message
I have tried to find him in the Members List, putting his name in the Search box, but the search strangely gave no result, although he is obviously a member of the group.
That is strange. All I can think of is that you typo'd the name, or accidentally included a space character or something else before or after the name in the search box.* Search in the Members list does partial matches, so you might try typing part of the name to make it easier.
Shal
* That's probably a bug report: search should ignore leading/trailing spaces I think.