Postfix not accepting recipient address: connect to private/policy: Connection refused

Postfix cannot process mail because your smtpd_recipient_restrictions configuration instructs to check_policy_service, but the referenced policy service cannot be queried (likely, because it is no longer started).

smtpd_recipient_restrictions = ..., check_policy_service unix:private/policy, ...

That setting specifies a UNIX socket path relative to the chroot (i.e. /var/spool/postfix/private), but neither does the name say what this is, nor does your master.cf contain a line that would make postfix start such policy service to listen on that socket.

Since your postconf -M dump does not mention it.. you may have unintentionally deleted a line in your master.cf that was supposed start it. If it was started by other means, it would not likely be placed into the private directory.

Did you setup any additional mail filters, like rate limiting, SPF or temporary deferrals ("greylisting")? If my guess is correct and this was previously configured in your master.cf, all you have to do is

• delete the references to the policy services from the restriction lists, if you are not using it, OR:
• re-add the lines in master.cf that define which program is actually called when the policy service unix:private/policy is queried.

You may find useful information on what was previously listening on that UNIX socket by investigating file ownership, or searching for logs mentioning private/policy but predating your recent changes.