I just updated the Let’s Encrypt implementation by moving it to a separate package: nethserver-letsencrypt.
I also created a new wiki page to help the testing process: http://wiki.nethserver.org/doku.php?id=developer:letsencrypt
@craaaft take a look, it should be a little bit more clear how it works! 
I’d like to invite everybody to contribute to the wiki page. LE is not simple, but really important. Sharing experiences will improve their and our implementation for sure.
Somehow it is not very convenient to share 80 port, we should implement port redirection.
HI @giacomo @filippo_carletti, on Clean NEW installation.
[root@mail etc]# /usr/libexec/nethserver/letsencrypt-certs -v
/usr/sbin/letsencrypt.sh --cron --config /etc/letsencrypt.sh/config.sh -d mail.dnis.pp.ua -d dnis.pp.ua
# INFO: Using main config file /etc/letsencrypt.sh/config.sh
+ Generating account key…
+ Registering account key with letsencrypt…
ERROR: WELLKNOWN directory doesn’t exist, please create /etc/letsencrypt.sh/.acme-challenges and set appropriate permissions.
I have modified config.sh script:
CHALLENGETYPE="http-01"
BASEDIR=/etc/letsencrypt.sh
WELLKNOWN="/var/www/html/.well-known/acme-challenge/"
As for now it works well.
Nevertheless, i have found out new version 1.1 on GitHub, so i’m looking forward for it 
I can’t reproduce the problem with packages on updates repository.
Ok ets Encrypt worked for me. Thanks for the help
Thank you! Now it works fine!
Will Letsencrypt be a standard feature of Nethserver going forward in version 7?
Yes. The plan is to have a single page in the UI to create a custom cert or install a commercial cert. In the same page, we plan to add letsencrypt.
BTW, letsencrypt is already available in v7a2.
They are leaving beta!