Situation:
A user with login xx@MyDomain.com was first only using a
external Yammer network. Let’s call it XYZInside.com
network. Than the company of the user created an own Yammer enterprise network.
Let’s call it MyDomain.com. The MyDomain.com, The user is now also joing the
Yammer network of its company. The Yammer network with the DNS suffix
MyDomain.com became now automatically the primary network for the user because
of the domain suffix for his login and of the Yammer network are the same.
The user now was disabled in the external network XYZInside.com
and could not be reactivated.
Solution: unchecked the option: “Require admin approval for MyDomain.com
members to join other companies' external networks.”
Only
available in Yammer enterprise networks
The user could join the external network in the past because
of he did that before the his now primary network with this policy enabled was
created.