Complete Mail Server Installation with Postfix and Dovecot
Comprehensive guide to set up a professional email server on Linux
Introduction and Architecture
What is a Mail Server?
A mail server handles sending and receiving emails. Our configuration uses two main components:
- Postfix: Mail Transfer Agent (MTA) - handles SMTP send/receive operations
- Dovecot: IMAP/POP3 Server - allows clients to access their emails
Global Architecture Diagram
┌─────────────────────────────────────────────────────────────────────────────┐
│ MAIL SERVER ARCHITECTURE │
└─────────────────────────────────────────────────────────────────────────────┘
INTERNET SERVER CLIENTS
──────── ────── ───────
┌──────────────┐ ┌─────────────────────────────┐
│ External │ Port 25 │ │
│ Server │ ──────────────▶│ POSTFIX │
│ (SMTP) │ │ (MTA - SMTP) │
└──────────────┘ │ │
│ ┌─────────────────────┐ │
│ │ Mail Queue │ │
│ │ │ │
│ └─────────────────────┘ │
│ │ │
│ ▼ │
│ ┌─────────────────────┐ │
│ │ Maildir │ │
│ │ /var/mail/vhosts/ │ │
│ └─────────────────────┘ │
│ │ │
└──────────────┼──────────────┘
│
┌──────────────┼──────────────┐
│ ▼ │
│ DOVECOT │ ┌──────────┐
│ (IMAP/POP3 Server) │────▶│ Outlook │
│ │ └──────────┘
│ Ports: 993 (IMAPS) │ ┌──────────┐
│ 995 (POP3S) │────▶│Thunderbird│
│ 587 (Submission) │ └──────────┘
└─────────────────────────────┘ ┌──────────┐
│ Webmail │
└──────────┘
Communication Flow
┌─────────────────────────────────────────────────────────────────────────────┐
│ INCOMING EMAIL FLOW │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐
│ External│ │ DNS │ │ Postfix │ │ Dovecot │ │ Mail │
│ Sender │ │ (MX) │ │ (MTA) │ │ (IMAP) │ │ Client │
└────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘
│ │ │ │ │
│ MX Query │ │ │ │
│──────────────▶│ │ │ │
│ │ │ │ │
│ MX Response │ │ │ │
│◀──────────────│ │ │ │
│ │ │ │ │
│ SMTP Connection (port 25) │ │
│──────────────────────────────▶│ │ │
│ │ │ │ │
│ │ │ Store in │ │
│ │ │ Maildir │ │
│ │ │──────────────▶│ │
│ │ │ │ │
│ │ │ │ IMAP │
│ │ │ │ Connection │
│ │ │ │ (993) │
│ │ │ │◀──────────────│
│ │ │ │ │
│ │ │ │ Emails │
│ │ │ │──────────────▶│
│ │ │ │ │
┌─────────────────────────────────────────────────────────────────────────────┐
│ OUTGOING EMAIL FLOW │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐
│ Mail │ │ Dovecot │ │ Postfix │ │ DNS │ │ Remote │
│ Client │ │ (Auth) │ │ (MTA) │ │ │ │ Server │
└────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘
│ │ │ │ │
│ SMTP Auth │ │ │ │
│ (port 587) │ │ │ │
│──────────────▶│ │ │ │
│ │ │ │ │
│ │ Validation │ │ │
│ │──────────────▶│ │ │
│ │ │ │ │
│ │ │ MX Query │ │
│ │ │──────────────▶│ │
│ │ │ │ │
│ │ │ MX Response │ │
│ │ │◀──────────────│ │
│ │ │ │ │
│ │ │ Send SMTP │ │
│ │ │──────────────────────────────▶│
│ │ │ │ │
Prerequisites
System Requirements
| Element | Minimum | Recommended |
|---|---|---|
| RAM | 512 MB | 2 GB |
| Storage | 10 GB | 50 GB+ |
| OS | Ubuntu 20.04+ / Debian 11+ | Ubuntu 22.04 LTS |
| Network | Static public IP | Dedicated IP |
Required Ports
┌─────────────────────────────────────────────────────────────────┐
│ REQUIRED NETWORK PORTS │
├────────┬──────────────┬─────────────────────────────────────────┤
│ Port │ Protocol │ Description │
├────────┼──────────────┼─────────────────────────────────────────┤
│ 25 │ SMTP │ Receive emails (server to server) │
│ 587 │ Submission │ Send emails (authenticated client) │
│ 465 │ SMTPS │ SMTP over SSL (legacy) │
│ 993 │ IMAPS │ IMAP over SSL (email access) │
│ 995 │ POP3S │ POP3 over SSL (email download) │
└────────┴──────────────┴─────────────────────────────────────────┘
Pre-flight Checks
# Check hostname
hostname -f
# Check if port 25 is not blocked
telnet smtp.google.com 25
# Check public IP
curl ifconfig.me
Package Installation
Ubuntu/Debian
# Update system
sudo apt update && sudo apt upgrade -y
# Install Postfix
sudo apt install postfix postfix-policyd-spf-python -y
# During installation, choose:
# - Configuration type: Internet Site
# - Mail name: your-domain.com
# Install Dovecot
sudo apt install dovecot-core dovecot-imapd dovecot-pop3d dovecot-lmtpd -y
# Additional tools
sudo apt install certbot mailutils -y
CentOS/RHEL
# Install EPEL repository
sudo dnf install epel-release -y
# Install Postfix
sudo dnf install postfix -y
# Install Dovecot
sudo dnf install dovecot dovecot-pigeonhole -y
# Enable services
sudo systemctl enable postfix dovecot
DNS Configuration
Required DNS Records
┌─────────────────────────────────────────────────────────────────────────────┐
│ REQUIRED DNS CONFIGURATION │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────┐
│ TYPE │ NAME │ VALUE │ TTL │
├────────┼────────────────────┼─────────────────────────────────┼────────────┤
│ A │ mail │ 203.0.113.10 │ 3600 │
│ MX │ @ │ 10 mail.your-domain.com │ 3600 │
│ TXT │ @ │ v=spf1 mx a -all │ 3600 │
│ TXT │ _dmarc │ v=DMARC1; p=quarantine │ 3600 │
│ PTR │ 10.113.0.203 │ mail.your-domain.com │ 3600 │
└────────┴────────────────────┴─────────────────────────────────┴────────────┘
Legend:
• A : Points "mail" subdomain to server IP
• MX : Indicates mail server for the domain
• TXT : SPF for outgoing email authentication
• TXT : DMARC for email handling policy
• PTR : Reverse DNS (configure with hosting provider)
DNS Verification
# Check MX record
dig MX your-domain.com +short
# Check A record
dig A mail.your-domain.com +short
# Check SPF
dig TXT your-domain.com +short
# Check reverse DNS
dig -x YOUR_PUBLIC_IP +short
Postfix Configuration
Postfix Internal Architecture
┌─────────────────────────────────────────────────────────────────────────────┐
│ POSTFIX INTERNAL ARCHITECTURE │
└─────────────────────────────────────────────────────────────────────────────┘
┌──────────────────┐
│ smtpd │◀─── Port 25 (incoming)
│ (reception) │◀─── Port 587 (submission)
└────────┬─────────┘
│
▼
┌──────────────────┐
│ cleanup │
│ (verification) │
└────────┬─────────┘
│
▼
┌──────────────────┐
│ qmgr │
│ (queue manager) │
│ │
└────────┬─────────┘
│
┌────────────────────────┼────────────────────────┐
│ │ │
▼ ▼ ▼
┌──────────────┐ ┌──────────────┐ ┌──────────────┐
│ smtp │ │ lmtp │ │ local │
│ (outgoing) │ │ (Dovecot) │ │ (system) │
└──────────────┘ └──────────────┘ └──────────────┘
│ │ │
▼ ▼ ▼
External servers Dovecot LMTP /var/mail/
File /etc/postfix/main.cf
# Create backup
sudo cp /etc/postfix/main.cf /etc/postfix/main.cf.backup
# Edit main configuration file
sudo nano /etc/postfix/main.cf
# =============================================================================
# POSTFIX - MAIN CONFIGURATION
# =============================================================================
# -----------------------------------------------------------------------------
# SERVER IDENTITY
# -----------------------------------------------------------------------------
myhostname = mail.your-domain.com
mydomain = your-domain.com
myorigin = $mydomain
# -----------------------------------------------------------------------------
# NETWORKS AND INTERFACES
# -----------------------------------------------------------------------------
inet_interfaces = all
inet_protocols = ipv4
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
# -----------------------------------------------------------------------------
# MAILBOXES
# -----------------------------------------------------------------------------
home_mailbox = Maildir/
mailbox_size_limit = 0
recipient_delimiter = +
# -----------------------------------------------------------------------------
# TLS/SSL
# -----------------------------------------------------------------------------
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.your-domain.com/fullchain.pem
smtpd_tls_key_file = /etc/letsencrypt/live/mail.your-domain.com/privkey.pem
smtpd_tls_security_level = may
smtpd_tls_auth_only = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
smtp_tls_security_level = may
smtp_tls_loglevel = 1
# Secure protocols and ciphers
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
# -----------------------------------------------------------------------------
# SASL AUTHENTICATION (via Dovecot)
# -----------------------------------------------------------------------------
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname
broken_sasl_auth_clients = yes
# -----------------------------------------------------------------------------
# RESTRICTIONS
# -----------------------------------------------------------------------------
smtpd_helo_required = yes
smtpd_helo_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_invalid_helo_hostname,
reject_non_fqdn_helo_hostname
smtpd_sender_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_non_fqdn_sender,
reject_unknown_sender_domain
smtpd_recipient_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_unauth_destination,
reject_non_fqdn_recipient,
reject_unknown_recipient_domain
# -----------------------------------------------------------------------------
# LIMITS AND PERFORMANCE
# -----------------------------------------------------------------------------
message_size_limit = 52428800
mailbox_size_limit = 0
smtpd_client_connection_count_limit = 10
smtpd_client_connection_rate_limit = 30
File /etc/postfix/master.cf
sudo nano /etc/postfix/master.cf
# =============================================================================
# POSTFIX - SERVICES
# =============================================================================
# Standard SMTP service (port 25)
smtp inet n - y - - smtpd
# Submission (port 587) - for authenticated clients
submission inet n - y - - smtpd
-o syslog_name=postfix/submission
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_tls_auth_only=yes
-o smtpd_reject_unlisted_recipient=no
-o smtpd_recipient_restrictions=permit_sasl_authenticated,reject
-o milter_macro_daemon_name=ORIGINATING
# SMTPS (port 465) - SMTP over SSL
smtps inet n - y - - smtpd
-o syslog_name=postfix/smtps
-o smtpd_tls_wrappermode=yes
-o smtpd_sasl_auth_enable=yes
-o smtpd_reject_unlisted_recipient=no
-o smtpd_recipient_restrictions=permit_sasl_authenticated,reject
-o milter_macro_daemon_name=ORIGINATING
Dovecot Configuration
Dovecot Internal Architecture
┌─────────────────────────────────────────────────────────────────────────────┐
│ DOVECOT INTERNAL ARCHITECTURE │
└─────────────────────────────────────────────────────────────────────────────┘
Mail Clients Dovecot Storage
──────────── ─────── ───────
┌────────────┐
│ Outlook │──┐
└────────────┘ │ ┌─────────────────────────────┐
│ │ │
┌────────────┐ │ IMAPS │ ┌─────────────────────┐ │
│Thunderbird │──┼────────▶│ │ imap-login │ │
└────────────┘ │ (993) │ │ (authentication) │ │
│ │ └──────────┬──────────┘ │
┌────────────┐ │ │ │ │
│ Mobile │──┘ │ ▼ │
└────────────┘ │ ┌─────────────────────┐ │ ┌───────────────┐
│ │ imap │ │ │ │
│ │ (protocol) │ │────▶│ Maildir │
│ └─────────────────────┘ │ │ │
│ │ │ /var/mail/ │
│ ┌─────────────────────┐ │ │ vhosts/ │
│ │ auth │───┼────▶│ domain/ │
│ │ (SASL) │ │ │ user/ │
│ └──────────┬──────────┘ │ │ │
│ │ │ └───────────────┘
│ ▼ │
│ ┌─────────────────────┐ │
Postfix ◀──────────│ │ auth-userdb │ │
(SASL) │ │ (socket) │ │
│ └─────────────────────┘ │
│ │
└─────────────────────────────┘
File /etc/dovecot/dovecot.conf
sudo nano /etc/dovecot/dovecot.conf
# =============================================================================
# DOVECOT - MAIN CONFIGURATION
# =============================================================================
# Enabled protocols
protocols = imap pop3 lmtp
# Listen on all interfaces
listen = *, ::
# Include modular configurations
!include conf.d/*.conf
File /etc/dovecot/conf.d/10-mail.conf
sudo nano /etc/dovecot/conf.d/10-mail.conf
# =============================================================================
# DOVECOT - MAIL STORAGE CONFIGURATION
# =============================================================================
# Mailbox location (Maildir format)
mail_location = maildir:~/Maildir
# Namespace for inbox
namespace inbox {
inbox = yes
}
# User/group for mail access
mail_uid = vmail
mail_gid = vmail
# Privileges
mail_privileged_group = mail
# First valid UID/GID
first_valid_uid = 1000
first_valid_gid = 1000
File /etc/dovecot/conf.d/10-auth.conf
sudo nano /etc/dovecot/conf.d/10-auth.conf
# =============================================================================
# DOVECOT - AUTHENTICATION
# =============================================================================
# Disable plaintext auth without SSL
disable_plaintext_auth = yes
# Authentication mechanisms
auth_mechanisms = plain login
# Include system configuration
!include auth-system.conf.ext
File /etc/dovecot/conf.d/10-ssl.conf
sudo nano /etc/dovecot/conf.d/10-ssl.conf
# =============================================================================
# DOVECOT - SSL/TLS CONFIGURATION
# =============================================================================
# Enable SSL
ssl = required
# Let's Encrypt certificates
ssl_cert = </etc/letsencrypt/live/mail.your-domain.com/fullchain.pem
ssl_key = </etc/letsencrypt/live/mail.your-domain.com/privkey.pem
# Allowed protocols (disable legacy)
ssl_min_protocol = TLSv1.2
# Prefer server ciphers
ssl_prefer_server_ciphers = yes
# Secure ciphers
ssl_cipher_list = ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384
File /etc/dovecot/conf.d/10-master.conf
sudo nano /etc/dovecot/conf.d/10-master.conf
# =============================================================================
# DOVECOT - SERVICES AND SOCKETS
# =============================================================================
service imap-login {
inet_listener imap {
port = 0 # Disabled (insecure)
}
inet_listener imaps {
port = 993
ssl = yes
}
}
service pop3-login {
inet_listener pop3 {
port = 0 # Disabled (insecure)
}
inet_listener pop3s {
port = 995
ssl = yes
}
}
service lmtp {
unix_listener /var/spool/postfix/private/dovecot-lmtp {
mode = 0600
user = postfix
group = postfix
}
}
# Authentication socket for Postfix
service auth {
unix_listener /var/spool/postfix/private/auth {
mode = 0666
user = postfix
group = postfix
}
unix_listener auth-userdb {
mode = 0600
user = vmail
}
user = dovecot
}
service auth-worker {
user = vmail
}
SSL/TLS Security
Obtain Let's Encrypt Certificate
# Temporarily stop services
sudo systemctl stop postfix dovecot
# Obtain certificate
sudo certbot certonly --standalone -d mail.your-domain.com
# Restart services
sudo systemctl start postfix dovecot
Automatic Renewal
# Create renewal script
sudo nano /etc/letsencrypt/renewal-hooks/post/mail-services.sh
#!/bin/bash
systemctl reload postfix
systemctl reload dovecot
# Make executable
sudo chmod +x /etc/letsencrypt/renewal-hooks/post/mail-services.sh
# Test renewal
sudo certbot renew --dry-run
SASL Authentication
Authentication Flow Diagram
┌─────────────────────────────────────────────────────────────────────────────┐
│ SASL AUTHENTICATION FLOW │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐
│ Mail │ │ Postfix │ │ Auth │ │ Dovecot │ │ PAM/ │
│ Client │ │ SMTP │ │ Socket │ │ Auth │ │ Passwd │
└────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘ └────┬────┘
│ │ │ │ │
│ EHLO │ │ │ │
│──────────────▶│ │ │ │
│ │ │ │ │
│ 250-AUTH │ │ │ │
│◀──────────────│ │ │ │
│ │ │ │ │
│ AUTH LOGIN │ │ │ │
│ user:pass │ │ │ │
│──────────────▶│ │ │ │
│ │ │ │ │
│ │ Verify │ │ │
│ │──────────────▶│ │ │
│ │ │ │ │
│ │ │ Check │ │
│ │ │──────────────▶│ │
│ │ │ │ │
│ │ │ │ Validate │
│ │ │ │──────────────▶│
│ │ │ │ │
│ │ │ │ OK/FAIL │
│ │ │ │◀─────────────│
│ │ │ │ │
│ │ │ Result │ │
│ │ │◀─────────────│ │
│ │ │ │ │
│ │ Result │ │ │
│ │◀─────────────│ │ │
│ │ │ │ │
│ 235 Auth OK │ │ │ │
│◀──────────────│ │ │ │
│ │ │ │ │
Create Mail User
# Create vmail group
sudo groupadd -g 5000 vmail
# Create vmail user
sudo useradd -g vmail -u 5000 vmail -d /var/mail
# Create storage directory
sudo mkdir -p /var/mail/vhosts/your-domain.com
# Set permissions
sudo chown -R vmail:vmail /var/mail/vhosts
# Create system user for mail
sudo useradd -m -s /bin/bash user1
sudo passwd user1
# Create Maildir structure
sudo -u user1 mkdir -p /home/user1/Maildir/{cur,new,tmp}
Testing and Validation
Complete Test Script
#!/bin/bash
# test-mail-server.sh
echo "=== Mail Server Test ==="
# Test 1: Check Postfix is listening
echo -n "Port 25 (SMTP): "
nc -zv localhost 25 2>&1 | grep -q "succeeded" && echo "OK" || echo "ERROR"
echo -n "Port 587 (Submission): "
nc -zv localhost 587 2>&1 | grep -q "succeeded" && echo "OK" || echo "ERROR"
# Test 2: Check Dovecot is listening
echo -n "Port 993 (IMAPS): "
nc -zv localhost 993 2>&1 | grep -q "succeeded" && echo "OK" || echo "ERROR"
echo -n "Port 995 (POP3S): "
nc -zv localhost 995 2>&1 | grep -q "succeeded" && echo "OK" || echo "ERROR"
# Test 3: Check SSL certificate
echo -n "SSL Certificate: "
openssl s_client -connect localhost:993 -servername mail.your-domain.com </dev/null 2>/dev/null | grep -q "Verify return code: 0" && echo "OK" || echo "CHECK"
# Test 4: Check Postfix configuration
echo -n "Postfix Configuration: "
postfix check 2>&1 | grep -q "error" && echo "ERROR" || echo "OK"
# Test 5: Check Dovecot configuration
echo -n "Dovecot Configuration: "
dovecot -n 2>&1 | grep -q "Error" && echo "ERROR" || echo "OK"
echo "=== Tests Complete ==="
Send Test Email
# Via command line
echo "This is a test" | mail -s "Test Email" [email protected]
# Check logs
sudo tail -f /var/log/mail.log
Test with Telnet/OpenSSL
# SMTP test
openssl s_client -connect mail.your-domain.com:587 -starttls smtp
# IMAP test
openssl s_client -connect mail.your-domain.com:993
Troubleshooting
Diagnostic Commands
# Check service status
sudo systemctl status postfix
sudo systemctl status dovecot
# Watch logs in real-time
sudo tail -f /var/log/mail.log
sudo tail -f /var/log/mail.err
# Check Postfix queue
sudo postqueue -p
# Force queue delivery
sudo postqueue -f
# Delete all queued messages
sudo postsuper -d ALL
# Test Postfix configuration
sudo postfix check
# Test Dovecot configuration
sudo doveconf -n
Common Issues
| Problem | Probable Cause | Solution |
|---|---|---|
| Connection refused port 25 | Postfix not running or port blocked | systemctl start postfix / Check firewall |
| SSL handshake failed | Invalid or expired certificate | Renew with certbot renew |
| Authentication failed | Wrong password or SASL config | Check /var/log/auth.log |
| Emails rejected | SPF/DKIM/DMARC misconfigured | Verify DNS records |
| Maildir not created | Incorrect permissions | chown -R vmail:vmail /var/mail |
Decision Tree
┌─────────────────────────────────────────────────────────────────────────────┐
│ TROUBLESHOOTING DECISION TREE │
└─────────────────────────────────────────────────────────────────────────────┘
┌─────────────────┐
│ Email not │
│ sending? │
└────────┬────────┘
│
┌───────────────┴───────────────┐
▼ ▼
┌───────────────┐ ┌───────────────┐
│ Service │ │ Service │
│ running? │ │ stopped │
└───────┬───────┘ └───────┬───────┘
│ │
▼ ▼
┌──────────────────┐ ┌──────────────────┐
│ Check mail.log │ │ systemctl start │
│ for errors │ │ postfix │
└────────┬─────────┘ └──────────────────┘
│
┌────────────┼────────────┐
▼ ▼ ▼
┌────────┐ ┌────────┐ ┌────────┐
│ Auth │ │ DNS │ │ Quota │
│ Error │ │ Error │ │ Error │
└───┬────┘ └───┬────┘ └───┬────┘
│ │ │
▼ ▼ ▼
┌────────┐ ┌────────┐ ┌────────┐
│Check │ │Check │ │Check │
│password│ │MX, SPF │ │disk │
│& SASL │ │DMARC │ │space │
└────────┘ └────────┘ └────────┘
File Summary
┌─────────────────────────────────────────────────────────────────────────────┐
│ CONFIGURATION FILE STRUCTURE │
└─────────────────────────────────────────────────────────────────────────────┘
/etc/
├── postfix/
│ ├── main.cf ← Main Postfix configuration
│ ├── master.cf ← Services and ports
│ └── main.cf.backup ← Backup
│
├── dovecot/
│ ├── dovecot.conf ← Main Dovecot configuration
│ └── conf.d/
│ ├── 10-mail.conf ← Mail storage
│ ├── 10-auth.conf ← Authentication
│ ├── 10-ssl.conf ← SSL certificates
│ └── 10-master.conf ← Services and sockets
│
└── letsencrypt/
└── live/
└── mail.your-domain.com/
├── fullchain.pem ← Certificate + chain
└── privkey.pem ← Private key
/var/
├── mail/
│ └── vhosts/
│ └── your-domain.com/ ← Mailboxes (Maildir)
│
└── log/
├── mail.log ← Main logs
└── mail.err ← Errors
Appendices
A. Useful Commands
# Service management
sudo systemctl {start|stop|restart|status} postfix
sudo systemctl {start|stop|restart|status} dovecot
# Logs
sudo journalctl -u postfix -f
sudo journalctl -u dovecot -f
# Queue
sudo postqueue -p # Show queue
sudo postsuper -d ALL # Clear queue
# Users
sudo doveadm user '*' # List users
B. Deployment Checklist
- DNS: A, MX, SPF, DMARC records configured
- Reverse DNS (PTR) configured
- SSL certificate obtained and valid
- Postfix configured and tested
- Dovecot configured and tested
- SASL authentication working
- Firewall: Ports 25, 587, 993, 995 open
- Send and receive test successful
- Automatic certificate renewal configured