Remove OUTCLEAN_ADDRESS

I believe that this isn't relevant anymore as we don't use OpenDKIM
anymore

Background on:
https://bofhskull.wordpress.com/2014/03/25/postfix-opendkim-and-missing-from-header/

core/postfix/conf/outclean_header_filter.cf

@@ -1,10 +1,7 @@
 # This configuration was copied from Mailinabox. The original version is available at:
 # https://raw.githubusercontent.com/mail-in-a-box/mailinabox/master/conf/postfix_outgoing_mail_header_filters
 
-# 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 ({{OUTCLEAN}} [{{OUTCLEAN_ADDRESS}}])$1
+/^\s*Received:[^\n]*(.*)/	IGNORE
 
 # Remove other typically private information.
 /^\s*User-Agent:/        IGNORE

core/postfix/start.py

@@ -46,15 +46,6 @@ 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]
-try:
-    _to_lookup = os.environ["OUTCLEAN"]
-    # Ensure we lookup a FQDN: @see #1884
-    if not _to_lookup.endswith('.'):
-        _to_lookup += '.'
-    os.environ["OUTCLEAN_ADDRESS"] = system.resolve_hostname(_to_lookup)
-except:
-    os.environ["OUTCLEAN_ADDRESS"] = "10.10.10.10"
 
 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/446.feature

@@ -0,0 +1 @@
+Remove the Received header with PRIMARY_HOSTNAME [PUBLIC_IP]