Hello,

I believe I have correctly followed the documentation for setting up an SSL certificate. However, I am using NixOS, so the setup isn’t standard, especially regarding certificate sharing.

I can log in to the Mailcow application successfully, but my browser shows an “unsecured” or “not secure” warning for the connection. I have confirmed that all necessary ports should be open and that port redirection is configured correctly.

For reference, here my mailcow.conf and nginx.nix configuration files

Any help or tips would be greatly appreciated, Thank you in advance!

# ------------------------------
# mailcow web ui configuration
# ------------------------------
# example.org is _not_ a valid hostname, use a fqdn here.
# Default admin user is "admin"
# Default password is "moohoo"

MAILCOW_HOSTNAME=mailcow.x.x

# Password hash algorithm
# Only certain password hash algorithm are supported. For a fully list of supported schemes,
# see https://docs.mailcow.email/models/model-passwd/
MAILCOW_PASS_SCHEME=BLF-CRYPT

# ------------------------------
# SQL database configuration
# ------------------------------

DBNAME=mailcow
DBUSER=mailcow

# Please use long, random alphanumeric strings (A-Za-z0-9)

DBPASS=x
DBROOT=x

# ------------------------------
# REDIS configuration
# ------------------------------

REDISPASS=x

# ------------------------------
# HTTP/S Bindings
# ------------------------------

# You should use HTTPS, but in case of SSL offloaded reverse proxies:
# Might be important: This will also change the binding within the container.
# If you use a proxy within Docker, point it to the ports you set below.
# Do _not_ use IP:PORT in HTTP(S)_BIND or HTTP(S)_PORT
# IMPORTANT: Do not use port 8081, 9081, 9082 or 65510!
# Example: HTTP_BIND=1.2.3.4
# For IPv4 leave it as it is: HTTP_BIND= & HTTPS_PORT=
# For IPv6 see https://docs.mailcow.email/post_installation/firststeps-ip_bindings/

HTTP_PORT=8084
HTTP_BIND=127.0.0.1

HTTPS_PORT=8443
HTTPS_BIND=

# Redirect HTTP connections to HTTPS - y/n
HTTP_REDIRECT=n

# ------------------------------
# Other bindings
# ------------------------------
# You should leave that alone
# Format: 11.22.33.44:25 or 12.34.56.78:465 etc.

SMTP_PORT=25
SMTPS_PORT=465
SUBMISSION_PORT=587
IMAP_PORT=143
IMAPS_PORT=993
POP_PORT=110
POPS_PORT=995
SIEVE_PORT=4190
DOVEADM_PORT=127.0.0.1:19991
SQL_PORT=127.0.0.1:13306
REDIS_PORT=127.0.0.1:7654

# Your timezone
# See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of timezones
# Use the column named 'TZ identifier' + pay attention for the column named 'Notes'

TZ=Europe/Paris

# Fixed project name
# Please use lowercase letters only

COMPOSE_PROJECT_NAME=mailcowdockerized

# Used Docker Compose version
# Switch here between native (compose plugin) and standalone
# For more informations take a look at the mailcow docs regarding the configuration options.
# Normally this should be untouched but if you decided to use either of those you can switch it manually here.
# Please be aware that at least one of those variants should be installed on your machine or mailcow will fail.

DOCKER_COMPOSE_VERSION=native

# Set this to "allow" to enable the anyone pseudo user. Disabled by default.
# When enabled, ACL can be created, that apply to "All authenticated users"
# This should probably only be activated on mail hosts, that are used exclusivly by one organisation.
# Otherwise a user might share data with too many other users.
ACL_ANYONE=disallow

# Garbage collector cleanup
# Deleted domains and mailboxes are moved to /var/vmail/_garbage/timestamp_sanitizedstring
# How long should objects remain in the garbage until they are being deleted? (value in minutes)
# Check interval is hourly

MAILDIR_GC_TIME=7200

# Additional SAN for the certificate
#
# You can use wildcard records to create specific names for every domain you add to mailcow.
# Example: Add domains "example.com" and "example.net" to mailcow, change ADDITIONAL_SAN to a value like:
#ADDITIONAL_SAN=imap.*,smtp.*
# This will expand the certificate to "imap.example.com", "smtp.example.com", "imap.example.net", "smtp.example.net"
# plus every domain you add in the future.
#
# You can also just add static names...
#ADDITIONAL_SAN=srv1.example.net
# ...or combine wildcard and static names:
#ADDITIONAL_SAN=imap.*,srv1.example.com
#

ADDITIONAL_SAN=

# Obtain certificates for autodiscover.* and autoconfig.* domains.
# This can be useful to switch off in case you are in a scenario where a reverse proxy already handles those.
# There are mixed scenarios where ports 80,443 are occupied and you do not want to share certs
# between services. So acme-mailcow obtains for maildomains and all web-things get handled
# in the reverse proxy.
AUTODISCOVER_SAN=y

# Additional server names for mailcow UI
#
# Specify alternative addresses for the mailcow UI to respond to
# This is useful when you set mail.* as ADDITIONAL_SAN and want to make sure mail.maildomain.com will always point to the mailcow UI.
# If the server name does not match a known site, Nginx decides by best-guess and may redirect users to the wrong web root.
# You can understand this as server_name directive in Nginx.
# Comma separated list without spaces! Example: ADDITIONAL_SERVER_NAMES=a.b.c,d.e.f

ADDITIONAL_SERVER_NAMES=mailcow.x.x

# Skip running ACME (acme-mailcow, Let's Encrypt certs) - y/n

SKIP_LETS_ENCRYPT=y

# Create seperate certificates for all domains - y/n
# this will allow adding more than 100 domains, but some email clients will not be able to connect with alternative hostnames
# see https://doc.dovecot.org/admin_manual/ssl/sni_support
ENABLE_SSL_SNI=n

# Skip IPv4 check in ACME container - y/n

SKIP_IP_CHECK=n

# Skip HTTP verification in ACME container - y/n

SKIP_HTTP_VERIFICATION=n

# Skip Unbound (DNS Resolver) Healthchecks (NOT Recommended!) - y/n

SKIP_UNBOUND_HEALTHCHECK=n

# Skip ClamAV (clamd-mailcow) anti-virus (Rspamd will auto-detect a missing ClamAV container) - y/n

SKIP_CLAMD=n

# Skip Olefy (olefy-mailcow) anti-virus for Office documents (Rspamd will auto-detect a missing Olefy container) - y/n

SKIP_OLEFY=n

# Skip SOGo: Will disable SOGo integration and therefore webmail, DAV protocols and ActiveSync support (experimental, unsupported, not fully implemented) - y/n

SKIP_SOGO=n

# Skip FTS (Fulltext Search) for Dovecot on low-memory, low-threaded systems or if you simply want to disable it.
# Dovecot inside mailcow use Flatcurve as FTS Backend.

SKIP_FTS=n

# Dovecot Indexing (FTS) Process maximum heap size in MB, there is no recommendation, please see Dovecot docs.
# Flatcurve (Xapian backend) is used as the FTS Indexer. It is supposed to be efficient in CPU and RAM consumption.
# However: Please always monitor your Resource consumption!

FTS_HEAP=128

# Controls how many processes the Dovecot indexing process can spawn at max.
# Too many indexing processes can use a lot of CPU and Disk I/O.
# Please visit: https://doc.dovecot.org/configuration_manual/service_configuration/#indexer-worker for more informations

FTS_PROCS=1

# Allow admins to log into SOGo as email user (without any password)

ALLOW_ADMIN_EMAIL_LOGIN=n

# Enable watchdog (watchdog-mailcow) to restart unhealthy containers

USE_WATCHDOG=y

# Send watchdog notifications by mail (sent from watchdog@MAILCOW_HOSTNAME)
# CAUTION:
# 1. You should use external recipients
# 2. Mails are sent unsigned (no DKIM)
# 3. If you use DMARC, create a separate DMARC policy ("v=DMARC1; p=none;" in _dmarc.MAILCOW_HOSTNAME)
# Multiple rcpts allowed, NO quotation marks, NO spaces

#WATCHDOG_NOTIFY_EMAIL=a@example.com,b@example.com,c@example.com
#WATCHDOG_NOTIFY_EMAIL=

# Send notifications to a webhook URL that receives a POST request with the content type "application/json".
# You can use this to send notifications to services like Discord, Slack and others.
#WATCHDOG_NOTIFY_WEBHOOK=https://discord.com/api/webhooks/XXXXXXXXXXXXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
# JSON body included in the webhook POST request. Needs to be in single quotes.
# Following variables are available: SUBJECT, BODY
#WATCHDOG_NOTIFY_WEBHOOK_BODY='{"username": "mailcow Watchdog", "content": "****\n"}'

# Notify about banned IP (includes whois lookup)
WATCHDOG_NOTIFY_BAN=n

# Send a notification when the watchdog is started.
WATCHDOG_NOTIFY_START=y

# Subject for watchdog mails. Defaults to "Watchdog ALERT" followed by the error message.
#WATCHDOG_SUBJECT=

# Checks if mailcow is an open relay. Requires a SAL. More checks will follow.
# https://www.servercow.de/mailcow?lang=en
# https://www.servercow.de/mailcow?lang=de
# No data is collected. Opt-in and anonymous.
# Will only work with unmodified mailcow setups.
WATCHDOG_EXTERNAL_CHECKS=n

# Enable watchdog verbose logging
WATCHDOG_VERBOSE=n

# Max log lines per service to keep in Redis logs

LOG_LINES=9999

# Internal IPv4 /24 subnet, format n.n.n (expands to n.n.n.0/24)
# Use private IPv4 addresses only, see https://en.wikipedia.org/wiki/Private_network#Private_IPv4_addresses

IPV4_NETWORK=172.22.1

# Internal IPv6 subnet in fc00::/7
# Use private IPv6 addresses only, see https://en.wikipedia.org/wiki/Private_network#Private_IPv6_addresses

IPV6_NETWORK=fd4d:6169:6c63:6f77::/64

# Use this IPv4 for outgoing connections (SNAT)

#SNAT_TO_SOURCE=

# Use this IPv6 for outgoing connections (SNAT)

#SNAT6_TO_SOURCE=

# Create or override an API key for the web UI
# You _must_ define API_ALLOW_FROM, which is a comma separated list of IPs
# An API key defined as API_KEY has read-write access
# An API key defined as API_KEY_READ_ONLY has read-only access
# Allowed chars for API_KEY and API_KEY_READ_ONLY: a-z, A-Z, 0-9, -
# You can define API_KEY and/or API_KEY_READ_ONLY

#API_KEY=
#API_KEY_READ_ONLY=
#API_ALLOW_FROM=172.22.1.1,127.0.0.1

# mail_home is ~/Maildir
MAILDIR_SUB=Maildir

# SOGo session timeout in minutes
SOGO_EXPIRE_SESSION=480

# DOVECOT_MASTER_USER and DOVECOT_MASTER_PASS must both be provided. No special chars.
# Empty by default to auto-generate master user and password on start.
# User expands to DOVECOT_MASTER_USER@mailcow.local
# LEAVE EMPTY IF UNSURE
DOVECOT_MASTER_USER=
# LEAVE EMPTY IF UNSURE
DOVECOT_MASTER_PASS=

# Let's Encrypt registration contact information
# Optional: Leave empty for none
# This value is only used on first order!
# Setting it at a later point will require the following steps:
# https://docs.mailcow.email/troubleshooting/debug-reset_tls/
ACME_CONTACT=

# WebAuthn device manufacturer verification
# After setting WEBAUTHN_ONLY_TRUSTED_VENDORS=y only devices from trusted manufacturers are allowed
# root certificates can be placed for validation under mailcow-dockerized/data/web/inc/lib/WebAuthn/rootCertificates
WEBAUTHN_ONLY_TRUSTED_VENDORS=n

# Spamhaus Data Query Service Key
# Optional: Leave empty for none
# Enter your key here if you are using a blocked ASN (OVH, AWS, Cloudflare e.g) for the unregistered Spamhaus Blocklist.
# If empty, it will completely disable Spamhaus blocklists if it detects that you are running on a server using a blocked AS.
# Otherwise it will work normally.
SPAMHAUS_DQS_KEY=

# Prevent netfilter from setting an iptables/nftables rule to isolate the mailcow docker network - y/n
# CAUTION: Disabling this may expose container ports to other neighbors on the same subnet, even if the ports are bound to localhost
DISABLE_NETFILTER_ISOLATION_RULE=n

# /etc/nixos/network/nginx.nix
{ config, pkgs, ... }:

{
  # --- Firewall Configuration ---
  networking.firewall.allowedTCPPorts = [ 80 443 25 110 143 465 587 993 995 4190 ];

  # --- ACME (Let's Encrypt) Configuration ---
  security.acme = {
    acceptTerms = true;
    defaults.email = "x@x.x";
  };

  # --- Nginx Service ---
  services.nginx = {
    enable = true;
    recommendedProxySettings = true;
    recommendedTlsSettings = true;
    
    virtualHosts = {
      # --- Virtual Host for Passbolt ---
      "passbolt.x.x" = {
        forceSSL = true;
        enableACME = true;
        locations."/" = {
          proxyPass = "http://127.0.0.1:8080";
          proxyWebsockets = true;
        };
      };

      "mailcow.x.x" = {
        forceSSL = true;
        enableACME = true;
        locations = {
          # Main proxy pass
          "/" = {
            proxyPass = "http://127.0.0.1:8084";
            proxyWebsockets = true;
          };

          # Required for Microsoft Exchange ActiveSync
          "/Microsoft-Server-ActiveSync" = {
            proxyPass = "http://127.0.0.1:8084/Microsoft-Server-ActiveSync";
          };
        };
      };
    };
  };
}