Replace PUBLIC_HOSTNAME/IP in Received headers

This will ensure that we don't get spam points for not respecting the
RFC

core/postfix/conf/outclean_header_filter.cf

@@ -4,7 +4,7 @@
 # Remove the first line of the Received: header. Note that we cannot fully remove the Received: header
 # because OpenDKIM requires that a header be present when signing outbound mail. The first line is
 # where the user's home IP address would be.
-/^\s*Received:[^\n]*(.*)/         REPLACE Received: from authenticated-user (PRIMARY_HOSTNAME [PUBLIC_IP])$1
+/^\s*Received:[^\n]*(.*)/         REPLACE Received: from authenticated-user ({{OUTCLEAN}} [{{OUTCLEAN_ADDRESS}}])$1
 
 # Remove other typically private information.
 /^\s*User-Agent:/        IGNORE

core/postfix/start.py

@@ -36,6 +36,8 @@ os.environ["FRONT_ADDRESS"] = system.get_host_address_from_environment("FRONT",
 os.environ["ADMIN_ADDRESS"] = system.get_host_address_from_environment("ADMIN", "admin")
 os.environ["ANTISPAM_MILTER_ADDRESS"] = system.get_host_address_from_environment("ANTISPAM_MILTER", "antispam:11332")
 os.environ["LMTP_ADDRESS"] = system.get_host_address_from_environment("LMTP", "imap:2525")
+os.environ["OUTCLEAN"] = os.environ["HOSTNAMES"].split(",")[0]
+os.environ["OUTCLEAN_ADDRESS"] = system.resolve_hostname(os.environ["OUTCLEAN"])
 
 for postfix_file in glob.glob("/conf/*.cf"):
     conf.jinja(postfix_file, os.environ, os.path.join("/etc/postfix", os.path.basename(postfix_file)))

towncrier/newsfragments/191.bugfix

@@ -0,0 +1 @@
+Replace PUBLIC_HOSTNAME and PUBLIC_IP in "Received" headers to ensure that no undue spam points are attributed