Add sympa (#2440)

* Add sympa

Sympa is a [popular]( https://www.sympa.org/users/custom )
mailing-list management software.

This commit can be tested [here](https://lists.riseup.net/www/)
and [here](https://wp.medicalistes.fr/wws) or even [here](http://lists1.kyxar.fr/sympa).

* Fix the ci ?

* meh