postfix/master.cf template: set smtpd syslog_name to "queue". Refs #2784
postfix/main.cf: suppress postconf warning

postconf: warning: /etc/postfix/main.cf: unused parameter: spfpolicy_time_limit=3600
postfix/main.cf: enforce strict checks on helo, sender, recipient addresses. Refs #2768

Imported restrictions from mail-common.
postfix sender_access table template: whitelisted senders skip strict sender checks. Refs #2768
Merge branch 'b2750'

Refs #2843 #2841 #2814 #2804 #2784 #2768 #2767 #2750 #2723