If you do not know if your users, groups and resources have the mail attribute, for Schema version 2 environments, use Delegated Administrator to check for mail services.
For Schema version 1 environments, use the csattribute list command with the -v (verbose) option.
For example, to check if the conference room resource Room100 has the mail attribute, you would issue the following command:
csattribute -v list Room100
The output tells if the mail attribute is present:
cn=Room 100,ou=conferenceRooms,dc=sesta,dc=com has mail: Room100@sesta.com
If the mailattribute exists, you do not have to add it. If the attribute does not exist, then add it as shown in the section that follows.