I have setup mailcow on my local Ubuntu server.
I have followed the guide to configure the DNS and Mailcow configuration.

So far I cannot receive (nor send) emails. I believe the sending part might be due to my ISP blocking the ports, and I am fine with that, but I would like to receive emails.

I have looked on this forum, reddit, google, youtube, and I have not found a solution.

I’m sure it is something stupid on my side but I have no idea where to look at this point.

I am using Traefik v3 as my reverse proxy and it is responsible to provide the SSL certificates.

Some error when sending emails:

05/13/2025, 01:15:34 PM	info	1A26DCD7F1: to=<some-email@gmail.com>, relay=none, delay=3345, delays=3280/0.02/65/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[2607:f8b0:4003:c04::1b]:25: Network is unreachable)
05/13/2025, 01:15:34 PM	info	connect to alt2.gmail-smtp-in.l.google.com[2607:f8b0:4003:c04::1b]:25: Network is unreachable
05/13/2025, 01:15:33 PM	info	connect to alt1.gmail-smtp-in.l.google.com[142.251.186.27]:25: Connection timed out

But I don’t see any error in the mailcow logs about receiving emails. I don’t see anything in traefik either.

DNS Configuration (Cloudflare):

domain.com	3600	IN	SOA	evan.ns.cloudflare.com. dns.cloudflare.com. 2049884481 10000 2400 604800 3600

;; NS Records
domain.com.	86400	IN	NS	evan.ns.cloudflare.com.
domain.com.	86400	IN	NS	tara.ns.cloudflare.com.

;; A Records
*.domain.com.	1	IN	A	x.x.x.x ; cf_tags=cf-proxied:false
domain.com.	1	IN	A	x.x.x.x ; cf_tags=cf-proxied:false
mail.domain.com.	1	IN	A	x.x.x.x ; cf_tags=cf-proxied:false

;; CNAME Records
autoconfig.domain.com.	1	IN	CNAME	mail.domain.com. ; cf_tags=cf-proxied:false
autodiscover.domain.com.	1	IN	CNAME	mail.domain.com. ; cf_tags=cf-proxied:false

;; MX Records
domain.com.	1	IN	MX	10 mail.domain.com.

;; TXT Records
domain.com.	1	IN	TXT	"v=spf1 mx a -all"
dkim._domainkey.domain.com.	1	IN	TXT	"v=DKIM1;k=rsa;t=s;s=email;p=key"
_dmarc.domain.com.	1	IN	TXT	"v=DMARC1; p=reject; rua=mailto:dmarc@domain.com"

Result of a nmap (Port forwarding is correctly setup on the router):

Starting Nmap 7.95 ( https://nmap.org ) at 2025-05-13 16:15 PDT
Nmap scan report for mail.domain.com (x.x.x.x)
Host is up (0.0055s latency).
Not shown: 990 closed tcp ports (reset)
PORT    STATE SERVICE
22/tcp  open  ssh
25/tcp  open  smtp
80/tcp  open  http
110/tcp open  pop3
143/tcp open  imap
443/tcp open  https
465/tcp open  smtps
587/tcp open  submission
993/tcp open  imaps
995/tcp open  pop3s

Nmap done: 1 IP address (1 host up) scanned in 0.34 seconds

Traefik config:

http:
  routers:
    # mail
    mail-public:
      entryPoints:
        - "https"
      rule: "Host(`mail.domain.com`)"
      middlewares:
        - default-headers
        - https-redirectscheme
      tls: { }
      service: mail

    autoconfig-public:
      entryPoints:
        - "https"
      rule: "Host(`autoconfig.domain.com`)"
      middlewares:
        - default-headers
        - https-redirectscheme
      tls: { }
      service: mail

    autodiscover-public:
      entryPoints:
        - "https"
      rule: "Host(`autodiscover.domain.com`)"
      middlewares:
        - default-headers
        - https-redirectscheme
      tls: { }
      service: mail


  services:
    mail:
      loadBalancer:
        servers:
          - url: "http://x.x.x.x:80"
        passHostHeader: true

  middlewares:
    https-redirectscheme:
      redirectScheme:
        scheme: https
        permanent: true

    default-headers:
      headers:
        frameDeny: true
        browserXssFilter: true
        contentTypeNosniff: true
        forceSTSHeader: true
        stsIncludeSubdomains: true
        stsPreload: true
        stsSeconds: 15552000
        customFrameOptionsValue: SAMEORIGIN
        customRequestHeaders:
          X-Forwarded-Proto: https

Mailcow Config file:

# ------------------------------
# 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=mail.domain.com

# 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=asdf
DBROOT=asdf

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

REDISPASS=asdf

# ------------------------------
# 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=80
HTTP_BIND=

HTTPS_PORT=443
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=America/Los_Angeles

# 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=n

# 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=

# 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