Dear Stefano,
ist seems, as if the last Update (3.1,3.1.1) caused a very similar problem again. Editors cannot enter den pages “Newsletters” and “Subscribers”, but for example the overview-pages of the plugin (although this access is blocked by another plugin).
Looks for me, as if there was a conflict with the plugin “adminimize”?
Going back to Version 3.0.9 solved the problem for me in the meantime.
Thanks in advance for some help!
Andreas