Edit /etc/e-smith/templates-custom/etc/yum/yum-cron.conf/20emitters and change emit_via = mail to emit_via = None
Apply the changes:
signal-event nethserver-base-update
This is a “bad” custom template as it overrides an existing fragment and future updates to yum-cron may not apply correcty but I didn’t find another way.
The tick-box is labelled: Send an email to the system administrator, not “other admins”.
If it’s supposed to activate/deactivate the custom recipients, then is should say that. Or better still only send e-mails if address are populated and remove the tick-box.
I would even go a bit further : I believe that no server should send “informative” emails. It should only send emails requiring attention. In this particular example yum sends a mail telling that there are updated packages, which is not relevant since it happens almost ever day.
An admin being flooded by those irrelevant emails could miss emails of vital importance, like a hard disk dying for instance.
That said, it looks like it is an upstream bug that was reported here :