How to change a Solaris zone netmask?

It is not recommended to edit  /etc/zones/zonename.xml file
zonecfg -z email-zone
zonecfg:email-zone> remove net address=174.1.130.132
zonecfg:email-zone> add net
zonecfg:email-zone:net> set address=174.1.130.232/24
zonecfg:email-zone:net> set physical=bge0
zonecfg:email-zone:net> end
zonecfg:email-zone> commit
zonecfg:email-zone> exit

Use this format for new-ip to configure a specific subnet mask: 174.1.130.132/24