logrotate-3.7.5-1 no longer depends on mailx (FS#6911) and no other
package in Core does.
FS#4812 says that mailx should depend on smtp-forwarder as
/usr/bin/mail calls /usr/sbin/sendmail.
Doing this will bring an interesting situation when a package in Core
depends on a virtual package provided by many of packages in Extra.
I suggest we remove mailx from Core completely (after
logrotate-3.7.5-1 will be signed off), because it's not required there