Alias_password alias option
Password protection for postings:
alias_password alias option specifies a password, or a comma-separated list of passwords, that allow posting to the list. An attempted posting to the list must contain one of these values on an Approved: header line in order for the posting to be allowed. During mailing list expansion, the password value will be removed from the Approved: header line; indeed, if that is the only value on the Approved: header line, then the entire header line will be removed. See Password-protected mailing lists.
In legacy configuration, the analogous alias file named parameter is
For aliases/lists defined in LDAP, the analogous setting is the LDAP attribute named by the
ldap_auth_password MTA option.