I am currently restricting a particular distribution group(s), meaning that only certain people can send mail to the restricted group(s). It worked perfectly before upgrade from 6.0.5, however after upgrade it no longer works.
Knowing the files created manually would not persist across upgrades, I did follow the directions again and have discovered the problem, but not sure how to correct the problem.
I made modifications to main.cf and created the other files as mentioned in RestrictPostfixRecipients, however each time Zimbra is restarted (either via zmcontrol or even with postfix reload), it does not persist. In either case, the line in main.cf: "smtpd_recipient_restrictions" is rewritten to default settings thus nullifying the change. When this occurs, there is no way to activate the settings required to enable the RestrictPostfixRecipients setting.
Until ZCS can put the functionality in the GUI, I don't know how to prevent main.cf from being rewritten completely. Only the lines in the file that are not commented out or non-default added (lines that do not exist in ZCS's config rewrite routines) are preserved. Any conflicting line like smtpd_recipient_restrictions, are wiped out at each postfix reload, even with the instructed postfix reload.