We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Override to use server hostname + IP in outbound headers
## What type of PR?
Enhancement

## What does this PR do?
Allows users to set the server IP and hostname in the outgoing "Received" header rather than "PUBLIC_HOSTNAME [PUBLIC_IP]".

### Related issue(s)
https://github.com/Mailu/Mailu/issues/191

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [ ] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `core/postfix/start.py`
Content:
```
1 #!/usr/bin/python3
2 
3 import os
4 import glob
5 import shutil
6 import multiprocessing
7 import logging as log
8 import sys
9 
10 from podop   import run_server
11 from socrate import system, conf
12 
13 log.basicConfig(stream=sys.stderr, level=os.environ.get("LOG_LEVEL", "WARNING"))
14 
15 def start_podop():
16     os.setuid(100)
17     url = "http://" + os.environ["ADMIN_ADDRESS"] + "/internal/postfix/"
18     # TODO: Remove verbosity setting from Podop?
19     run_server(0, "postfix", "/tmp/podop.socket", [
20 		("transport", "url", url + "transport/§"),
21 		("alias", "url", url + "alias/§"),
22 		("domain", "url", url + "domain/§"),
23         ("mailbox", "url", url + "mailbox/§"),
24         ("recipientmap", "url", url + "recipient/map/§"),
25         ("sendermap", "url", url + "sender/map/§"),
26         ("senderaccess", "url", url + "sender/access/§"),
27         ("senderlogin", "url", url + "sender/login/§")
28     ])
29 
30 def is_valid_postconf_line(line):
31     return not line.startswith("#") \
32             and not line == ''
33 
34 # Actual startup script
35 os.environ["FRONT_ADDRESS"] = system.get_host_address_from_environment("FRONT", "front")
36 os.environ["ADMIN_ADDRESS"] = system.get_host_address_from_environment("ADMIN", "admin")
37 os.environ["ANTISPAM_MILTER_ADDRESS"] = system.get_host_address_from_environment("ANTISPAM_MILTER", "antispam:11332")
38 os.environ["LMTP_ADDRESS"] = system.get_host_address_from_environment("LMTP", "imap:2525")
39 
40 for postfix_file in glob.glob("/conf/*.cf"):
41     conf.jinja(postfix_file, os.environ, os.path.join("/etc/postfix", os.path.basename(postfix_file)))
42 
43 if os.path.exists("/overrides/postfix.cf"):
44     for line in open("/overrides/postfix.cf").read().strip().split("\n"):
45         if is_valid_postconf_line(line):
46             os.system('postconf -e "{}"'.format(line))
47 
48 if os.path.exists("/overrides/postfix.master"):
49     for line in open("/overrides/postfix.master").read().strip().split("\n"):
50         if is_valid_postconf_line(line):
51             os.system('postconf -Me "{}"'.format(line))
52 
53 for map_file in glob.glob("/overrides/*.map"):
54     destination = os.path.join("/etc/postfix", os.path.basename(map_file))
55     shutil.copyfile(map_file, destination)
56     os.system("postmap {}".format(destination))
57     os.remove(destination)
58 
59 if "RELAYUSER" in os.environ:
60     path = "/etc/postfix/sasl_passwd"
61     conf.jinja("/conf/sasl_passwd", os.environ, path)
62     os.system("postmap {}".format(path))
63 
64 # Run Podop and Postfix
65 multiprocessing.Process(target=start_podop).start()
66 os.system("/usr/libexec/postfix/post-install meta_directory=/etc/postfix create-missing")
67 # Before starting postfix, we need to check permissions on /queue
68 # in the event that postfix,postdrop id have changed
69 os.system("postfix set-permissions")
70 os.system("postfix start-fg")
71
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/core/postfix/start.py b/core/postfix/start.py
--- a/core/postfix/start.py
+++ b/core/postfix/start.py
@@ -36,6 +36,11 @@
 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:
+    os.environ["OUTCLEAN_ADDRESS"] = system.resolve_hostname(os.environ["OUTCLEAN"])
+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)))

{"golden_diff": "diff --git a/core/postfix/start.py b/core/postfix/start.py\n--- a/core/postfix/start.py\n+++ b/core/postfix/start.py\n@@ -36,6 +36,11 @@\n os.environ[\"ADMIN_ADDRESS\"] = system.get_host_address_from_environment(\"ADMIN\", \"admin\")\n os.environ[\"ANTISPAM_MILTER_ADDRESS\"] = system.get_host_address_from_environment(\"ANTISPAM_MILTER\", \"antispam:11332\")\n os.environ[\"LMTP_ADDRESS\"] = system.get_host_address_from_environment(\"LMTP\", \"imap:2525\")\n+os.environ[\"OUTCLEAN\"] = os.environ[\"HOSTNAMES\"].split(\",\")[0]\n+try:\n+    os.environ[\"OUTCLEAN_ADDRESS\"] = system.resolve_hostname(os.environ[\"OUTCLEAN\"])\n+except:\n+    os.environ[\"OUTCLEAN_ADDRESS\"] = \"10.10.10.10\"\n \n for postfix_file in glob.glob(\"/conf/*.cf\"):\n     conf.jinja(postfix_file, os.environ, os.path.join(\"/etc/postfix\", os.path.basename(postfix_file)))\n", "issue": "Override to use server hostname + IP in outbound headers\n## What type of PR?\r\nEnhancement\r\n\r\n## What does this PR do?\r\nAllows users to set the server IP and hostname in the outgoing \"Received\" header rather than \"PUBLIC_HOSTNAME [PUBLIC_IP]\".\r\n\r\n### Related issue(s)\r\nhttps://github.com/Mailu/Mailu/issues/191\r\n\r\n## Prerequistes\r\nBefore we can consider review and merge, please make sure the following list is done and checked.\r\nIf an entry in not applicable, you can check it or remove it from the list.\r\n\r\n- [x] In case of feature or enhancement: documentation updated accordingly\r\n- [ ] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/guide.html#changelog) entry file.\r\n\n", "before_files": [{"content": "#!/usr/bin/python3\n\nimport os\nimport glob\nimport shutil\nimport multiprocessing\nimport logging as log\nimport sys\n\nfrom podop   import run_server\nfrom socrate import system, conf\n\nlog.basicConfig(stream=sys.stderr, level=os.environ.get(\"LOG_LEVEL\", \"WARNING\"))\n\ndef start_podop():\n    os.setuid(100)\n    url = \"http://\" + os.environ[\"ADMIN_ADDRESS\"] + \"/internal/postfix/\"\n    # TODO: Remove verbosity setting from Podop?\n    run_server(0, \"postfix\", \"/tmp/podop.socket\", [\n\t\t(\"transport\", \"url\", url + \"transport/\u00a7\"),\n\t\t(\"alias\", \"url\", url + \"alias/\u00a7\"),\n\t\t(\"domain\", \"url\", url + \"domain/\u00a7\"),\n        (\"mailbox\", \"url\", url + \"mailbox/\u00a7\"),\n        (\"recipientmap\", \"url\", url + \"recipient/map/\u00a7\"),\n        (\"sendermap\", \"url\", url + \"sender/map/\u00a7\"),\n        (\"senderaccess\", \"url\", url + \"sender/access/\u00a7\"),\n        (\"senderlogin\", \"url\", url + \"sender/login/\u00a7\")\n    ])\n\ndef is_valid_postconf_line(line):\n    return not line.startswith(\"#\") \\\n            and not line == ''\n\n# Actual startup script\nos.environ[\"FRONT_ADDRESS\"] = system.get_host_address_from_environment(\"FRONT\", \"front\")\nos.environ[\"ADMIN_ADDRESS\"] = system.get_host_address_from_environment(\"ADMIN\", \"admin\")\nos.environ[\"ANTISPAM_MILTER_ADDRESS\"] = system.get_host_address_from_environment(\"ANTISPAM_MILTER\", \"antispam:11332\")\nos.environ[\"LMTP_ADDRESS\"] = system.get_host_address_from_environment(\"LMTP\", \"imap:2525\")\n\nfor postfix_file in glob.glob(\"/conf/*.cf\"):\n    conf.jinja(postfix_file, os.environ, os.path.join(\"/etc/postfix\", os.path.basename(postfix_file)))\n\nif os.path.exists(\"/overrides/postfix.cf\"):\n    for line in open(\"/overrides/postfix.cf\").read().strip().split(\"\\n\"):\n        if is_valid_postconf_line(line):\n            os.system('postconf -e \"{}\"'.format(line))\n\nif os.path.exists(\"/overrides/postfix.master\"):\n    for line in open(\"/overrides/postfix.master\").read().strip().split(\"\\n\"):\n        if is_valid_postconf_line(line):\n            os.system('postconf -Me \"{}\"'.format(line))\n\nfor map_file in glob.glob(\"/overrides/*.map\"):\n    destination = os.path.join(\"/etc/postfix\", os.path.basename(map_file))\n    shutil.copyfile(map_file, destination)\n    os.system(\"postmap {}\".format(destination))\n    os.remove(destination)\n\nif \"RELAYUSER\" in os.environ:\n    path = \"/etc/postfix/sasl_passwd\"\n    conf.jinja(\"/conf/sasl_passwd\", os.environ, path)\n    os.system(\"postmap {}\".format(path))\n\n# Run Podop and Postfix\nmultiprocessing.Process(target=start_podop).start()\nos.system(\"/usr/libexec/postfix/post-install meta_directory=/etc/postfix create-missing\")\n# Before starting postfix, we need to check permissions on /queue\n# in the event that postfix,postdrop id have changed\nos.system(\"postfix set-permissions\")\nos.system(\"postfix start-fg\")\n", "path": "core/postfix/start.py"}], "after_files": [{"content": "#!/usr/bin/python3\n\nimport os\nimport glob\nimport shutil\nimport multiprocessing\nimport logging as log\nimport sys\n\nfrom podop   import run_server\nfrom socrate import system, conf\n\nlog.basicConfig(stream=sys.stderr, level=os.environ.get(\"LOG_LEVEL\", \"WARNING\"))\n\ndef start_podop():\n    os.setuid(100)\n    url = \"http://\" + os.environ[\"ADMIN_ADDRESS\"] + \"/internal/postfix/\"\n    # TODO: Remove verbosity setting from Podop?\n    run_server(0, \"postfix\", \"/tmp/podop.socket\", [\n\t\t(\"transport\", \"url\", url + \"transport/\u00a7\"),\n\t\t(\"alias\", \"url\", url + \"alias/\u00a7\"),\n\t\t(\"domain\", \"url\", url + \"domain/\u00a7\"),\n        (\"mailbox\", \"url\", url + \"mailbox/\u00a7\"),\n        (\"recipientmap\", \"url\", url + \"recipient/map/\u00a7\"),\n        (\"sendermap\", \"url\", url + \"sender/map/\u00a7\"),\n        (\"senderaccess\", \"url\", url + \"sender/access/\u00a7\"),\n        (\"senderlogin\", \"url\", url + \"sender/login/\u00a7\")\n    ])\n\ndef is_valid_postconf_line(line):\n    return not line.startswith(\"#\") \\\n            and not line == ''\n\n# Actual startup script\nos.environ[\"FRONT_ADDRESS\"] = system.get_host_address_from_environment(\"FRONT\", \"front\")\nos.environ[\"ADMIN_ADDRESS\"] = system.get_host_address_from_environment(\"ADMIN\", \"admin\")\nos.environ[\"ANTISPAM_MILTER_ADDRESS\"] = system.get_host_address_from_environment(\"ANTISPAM_MILTER\", \"antispam:11332\")\nos.environ[\"LMTP_ADDRESS\"] = system.get_host_address_from_environment(\"LMTP\", \"imap:2525\")\nos.environ[\"OUTCLEAN\"] = os.environ[\"HOSTNAMES\"].split(\",\")[0]\ntry:\n    os.environ[\"OUTCLEAN_ADDRESS\"] = system.resolve_hostname(os.environ[\"OUTCLEAN\"])\nexcept:\n    os.environ[\"OUTCLEAN_ADDRESS\"] = \"10.10.10.10\"\n\nfor postfix_file in glob.glob(\"/conf/*.cf\"):\n    conf.jinja(postfix_file, os.environ, os.path.join(\"/etc/postfix\", os.path.basename(postfix_file)))\n\nif os.path.exists(\"/overrides/postfix.cf\"):\n    for line in open(\"/overrides/postfix.cf\").read().strip().split(\"\\n\"):\n        if is_valid_postconf_line(line):\n            os.system('postconf -e \"{}\"'.format(line))\n\nif os.path.exists(\"/overrides/postfix.master\"):\n    for line in open(\"/overrides/postfix.master\").read().strip().split(\"\\n\"):\n        if is_valid_postconf_line(line):\n            os.system('postconf -Me \"{}\"'.format(line))\n\nfor map_file in glob.glob(\"/overrides/*.map\"):\n    destination = os.path.join(\"/etc/postfix\", os.path.basename(map_file))\n    shutil.copyfile(map_file, destination)\n    os.system(\"postmap {}\".format(destination))\n    os.remove(destination)\n\nif \"RELAYUSER\" in os.environ:\n    path = \"/etc/postfix/sasl_passwd\"\n    conf.jinja(\"/conf/sasl_passwd\", os.environ, path)\n    os.system(\"postmap {}\".format(path))\n\n# Run Podop and Postfix\nmultiprocessing.Process(target=start_podop).start()\nos.system(\"/usr/libexec/postfix/post-install meta_directory=/etc/postfix create-missing\")\n# Before starting postfix, we need to check permissions on /queue\n# in the event that postfix,postdrop id have changed\nos.system(\"postfix set-permissions\")\nos.system(\"postfix start-fg\")\n", "path": "core/postfix/start.py"}]}