[Samba] read only user

[Terry]

Hi I need to have a list of users with read write and one user read only
I have this at the moment

[global]
workgroup =workgroup
netbios name = server
encrypt passwords=yes
printcap name = /etc/printcap
security = share


[main]
        path = /usr/server-shares/main
        valid users = user1 user2 user3
        write list = user1 user2

so in the above should user3 be able to read only ?
from what i heard today user3 can read only but the other two cant write