I notice here that Canonical has partnered with Zentyal - does that make them an official derivative?
although we (Zentyal) are Canonical partners to include official Ubuntu support for our customers, we are not currently an official Ubuntu derivative.
For any kind of questions you can use our forums (forum.zentyal.org). We are also attending to the UDS-r where you can meet us in person and ask us directly.
Zentyal is a distribution which provides "server to small and medium sized Business (SMB)". It is based on Ubuntu. But, it is not an official Ubuntu derivative like Kubuntu, Xubuntu etc. The officially recognized Ubuntu derivatives are listed here
These includes the following distributions:
We can recognize an official derivative. An official derivative should
But, Zentyal uses their customized repositories as listed here.
Another important point to notice is, As being an independent company Canonical can co-operate on another project and as far as I know, that doesn't make the project an Official one. Also, To be recognized as an official derivative the project need to significantly contribute to the main Ubuntu project.