Configuring Email Integration on Alpine Linux 📧

Email integration is essential for system notifications, web applications, and communication services. This guide will help you set up a complete email infrastructure on Alpine Linux, including both sending and receiving capabilities.

Table of Contents

• Prerequisites
• Understanding Email Services
• Installing Postfix (SMTP)
• Configuring Dovecot (IMAP/POP3)
• Setting Up Authentication
• SSL/TLS Configuration
• Spam Filtering with SpamAssassin
• Virus Scanning with ClamAV
• Webmail Installation
• Email Client Configuration
• Application Integration
• Monitoring and Logging
• Backup and Migration
• Troubleshooting
• Best Practices
• Conclusion

Prerequisites

Before configuring email services, ensure you have:

• Alpine Linux with root access
• Valid domain name with MX records
• Static IP address (for mail server)
• SSL certificate for secure connections
• Basic understanding of DNS and email protocols
• At least 2GB RAM for full mail server

Understanding Email Services

Email Components

# Check current mail setup
which sendmail
ls -la /var/spool/mail/

Key components:

• MTA (Mail Transfer Agent): Postfix for sending/receiving
• MDA (Mail Delivery Agent): Dovecot for storage/retrieval
• MUA (Mail User Agent): Client applications
• Authentication: SASL for secure login

Installing Postfix (SMTP)

Step 1: Install Postfix

# Update package repository
apk update

# Install Postfix
apk add postfix postfix-pcre postfix-mysql

# Install utilities
apk add mailx cyrus-sasl cyrus-sasl-plain cyrus-sasl-login

# Enable Postfix service
rc-update add postfix default

Step 2: Basic Postfix Configuration

# Backup original configuration
cp /etc/postfix/main.cf /etc/postfix/main.cf.backup

# Configure Postfix
cat > /etc/postfix/main.cf << 'EOF'
# Basic configuration
myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks = 127.0.0.0/8, 192.168.0.0/16
inet_interfaces = all
inet_protocols = ipv4

# Mail directories
home_mailbox = Maildir/
mail_spool_directory = /var/spool/mail

# Queue settings
maximal_queue_lifetime = 1d
bounce_queue_lifetime = 1d
maximal_backoff_time = 1h
minimal_backoff_time = 5m
queue_run_delay = 5m

# Message size limits
message_size_limit = 52428800
mailbox_size_limit = 1073741824

# Security settings
smtpd_banner = $myhostname ESMTP
biff = no
append_dot_mydomain = no
readme_directory = no

# TLS parameters
smtpd_tls_cert_file = /etc/ssl/certs/mail.crt
smtpd_tls_key_file = /etc/ssl/private/mail.key
smtpd_use_tls = yes
smtpd_tls_security_level = may
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# SASL authentication
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname

# Restrictions
smtpd_recipient_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_unauth_destination,
    reject_invalid_hostname,
    reject_non_fqdn_hostname,
    reject_non_fqdn_sender,
    reject_non_fqdn_recipient,
    reject_unknown_sender_domain,
    reject_unknown_recipient_domain,
    reject_rbl_client zen.spamhaus.org,
    permit

smtpd_sender_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_non_fqdn_sender,
    reject_unknown_sender_domain,
    permit

smtpd_relay_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    defer_unauth_destination
EOF

Step 3: Configure Master Process

# Configure master.cf
cat > /etc/postfix/master.cf << 'EOF'
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
# ==========================================================================
smtp      inet  n       -       y       -       -       smtpd
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     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
pickup    unix  n       -       y       60      1       pickup
cleanup   unix  n       -       y       -       0       cleanup
qmgr      unix  n       -       n       300     1       qmgr
tlsmgr    unix  -       -       y       1000?   1       tlsmgr
rewrite   unix  -       -       y       -       -       trivial-rewrite
bounce    unix  -       -       y       -       0       bounce
defer     unix  -       -       y       -       0       bounce
trace     unix  -       -       y       -       0       bounce
verify    unix  -       -       y       -       1       verify
flush     unix  n       -       y       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       y       -       -       smtp
relay     unix  -       -       y       -       -       smtp
showq     unix  n       -       y       -       -       showq
error     unix  -       -       y       -       -       error
retry     unix  -       -       y       -       -       error
discard   unix  -       -       y       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       y       -       -       lmtp
anvil     unix  -       -       y       -       1       anvil
scache    unix  -       -       y       -       1       scache
EOF

Configuring Dovecot (IMAP/POP3)

Step 1: Install Dovecot

# Install Dovecot
apk add dovecot dovecot-lmtpd dovecot-pop3d dovecot-mysql dovecot-pigeonhole-plugin

# Enable Dovecot service
rc-update add dovecot default

Step 2: Configure Dovecot

# Main configuration
cat > /etc/dovecot/dovecot.conf << 'EOF'
# Protocols to enable
protocols = imap pop3 lmtp

# Listen addresses
listen = *, ::

# Base directory
base_dir = /var/run/dovecot/

# Greeting message
login_greeting = Mail Server Ready.

# SSL/TLS configuration
ssl = required
ssl_cert = </etc/ssl/certs/mail.crt
ssl_key = </etc/ssl/private/mail.key
ssl_min_protocol = TLSv1.2
ssl_cipher_list = HIGH:!aNULL:!MD5
ssl_prefer_server_ciphers = yes

# Authentication
auth_mechanisms = plain login
disable_plaintext_auth = yes

# Mail location
mail_location = maildir:~/Maildir

# User database
userdb {
    driver = passwd
}

# Password database
passdb {
    driver = pam
}

# Services
service imap-login {
    inet_listener imap {
        port = 143
    }
    inet_listener imaps {
        port = 993
        ssl = yes
    }
}

service pop3-login {
    inet_listener pop3 {
        port = 110
    }
    inet_listener pop3s {
        port = 995
        ssl = yes
    }
}

service auth {
    unix_listener /var/spool/postfix/private/auth {
        mode = 0660
        user = postfix
        group = postfix
    }
}

service lmtp {
    unix_listener /var/spool/postfix/private/dovecot-lmtp {
        mode = 0600
        user = postfix
        group = postfix
    }
}

# Logging
log_path = /var/log/dovecot.log
info_log_path = /var/log/dovecot-info.log
debug_log_path = /var/log/dovecot-debug.log

# Plugin configuration
plugin {
    sieve = ~/.dovecot.sieve
    sieve_dir = ~/sieve
}

# Protocol specific settings
protocol imap {
    mail_plugins = $mail_plugins
    imap_client_workarounds = delay-newmail
}

protocol pop3 {
    mail_plugins = $mail_plugins
    pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}

protocol lmtp {
    mail_plugins = $mail_plugins sieve
}
EOF

Step 3: Configure Mailbox Settings

# Create mail directories configuration
cat > /etc/dovecot/conf.d/10-mail.conf << 'EOF'
# Mail location and namespace
mail_location = maildir:~/Maildir

namespace inbox {
    inbox = yes
    
    mailbox Drafts {
        special_use = \Drafts
        auto = create
    }
    mailbox Junk {
        special_use = \Junk
        auto = create
    }
    mailbox Trash {
        special_use = \Trash
        auto = create
    }
    mailbox Sent {
        special_use = \Sent
        auto = create
    }
}

# Mail UID/GID
mail_uid = vmail
mail_gid = vmail

# Performance settings
mail_fsync = optimized
mmap_disable = yes
mail_nfs_storage = no
mail_nfs_index = no
EOF

# Create vmail user
addgroup -g 5000 vmail
adduser -u 5000 -G vmail -h /var/mail -D -s /sbin/nologin vmail

Setting Up Authentication

Step 1: Configure SASL Authentication

# Create SASL configuration
cat > /etc/sasl2/smtpd.conf << 'EOF'
pwcheck_method: saslauthd
mech_list: PLAIN LOGIN
saslauthd_path: /var/run/saslauthd/mux
EOF

# Start saslauthd
rc-update add saslauthd default
rc-service saslauthd start

Step 2: Virtual User Setup

# Create virtual user database
cat > /etc/postfix/virtual_mailbox_domains << 'EOF'
example.com     OK
subdomain.example.com   OK
EOF

# Create virtual mailbox mapping
cat > /etc/postfix/virtual_mailbox_maps << 'EOF'
[email protected]       example.com/admin/
[email protected]        example.com/info/
[email protected]        example.com/user/
EOF

# Hash the maps
postmap /etc/postfix/virtual_mailbox_domains
postmap /etc/postfix/virtual_mailbox_maps

# Update Postfix configuration
cat >> /etc/postfix/main.cf << 'EOF'

# Virtual domains
virtual_mailbox_domains = hash:/etc/postfix/virtual_mailbox_domains
virtual_mailbox_base = /var/mail/vhosts
virtual_mailbox_maps = hash:/etc/postfix/virtual_mailbox_maps
virtual_minimum_uid = 5000
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
EOF

SSL/TLS Configuration

Step 1: Generate SSL Certificates

# Generate self-signed certificate (for testing)
openssl req -new -x509 -days 365 -nodes -newkey rsa:4096 \
    -keyout /etc/ssl/private/mail.key \
    -out /etc/ssl/certs/mail.crt \
    -subj "/C=US/ST=State/L=City/O=Organization/CN=mail.example.com"

# Set permissions
chmod 600 /etc/ssl/private/mail.key
chmod 644 /etc/ssl/certs/mail.crt

Step 2: Let’s Encrypt Certificate

# Install certbot
apk add certbot

# Obtain certificate
certbot certonly --standalone -d mail.example.com -d smtp.example.com -d imap.example.com

# Create renewal hook
cat > /etc/periodic/daily/renew-mail-cert << 'EOF'
#!/bin/sh
certbot renew --quiet --no-self-upgrade --post-hook "rc-service postfix reload && rc-service dovecot reload"
EOF

chmod +x /etc/periodic/daily/renew-mail-cert

Spam Filtering with SpamAssassin

Step 1: Install SpamAssassin

# Install SpamAssassin
apk add spamassassin spamassassin-client perl-mail-spf

# Create SpamAssassin user
adduser -D -s /sbin/nologin -h /var/lib/spamassassin spamd

# Enable service
rc-update add spamd default

Step 2: Configure SpamAssassin

# Configure SpamAssassin
cat > /etc/mail/spamassassin/local.cf << 'EOF'
# Basic configuration
rewrite_header Subject [SPAM]
report_safe 0
required_score 5.0
use_bayes 1
bayes_auto_learn 1
skip_rbl_checks 0

# Network tests
dns_available yes
razor_config /etc/mail/spamassassin/.razor/razor-agent.conf
pyzor_options --homedir /etc/mail/spamassassin/.pyzor

# Whitelist
whitelist_from *@example.com
whitelist_from_rcvd *@trustedomain.com

# Custom scores
score URIBL_BLACK 3.0
score URIBL_GREY 1.5
score HTML_MESSAGE 0.5
EOF

# Update SpamAssassin rules
sa-update

# Configure Postfix integration
cat >> /etc/postfix/master.cf << 'EOF'

# SpamAssassin filter
spamassassin unix -     n       n       -       -       pipe
  user=spamd argv=/usr/bin/spamc -f -e
  /usr/sbin/sendmail -oi -f ${sender} ${recipient}
EOF

# Update main.cf
echo "content_filter = spamassassin" >> /etc/postfix/main.cf

Virus Scanning with ClamAV

Step 1: Install ClamAV

# Install ClamAV
apk add clamav clamav-daemon clamav-scanner clamav-libunrar

# Update virus database
freshclam

# Configure ClamAV
sed -i 's/^Example/#Example/' /etc/clamav/clamd.conf
sed -i 's/^Example/#Example/' /etc/clamav/freshclam.conf

# Enable services
rc-update add clamd default
rc-update add freshclam default
rc-service clamd start
rc-service freshclam start

Step 2: Integrate with Postfix

# Install clamsmtp
apk add clamsmtp

# Configure clamsmtp
cat > /etc/clamsmtpd.conf << 'EOF'
OutAddress: 127.0.0.1:10026
Listen: 127.0.0.1:10025
TempDirectory: /var/spool/clamsmtp
User: clamsmtp
Action: drop
Quarantine: on
QuarantineDir: /var/spool/clamsmtp/quarantine
VirusAction: reject
XHeaders: on
EOF

# Update Postfix configuration
cat >> /etc/postfix/main.cf << 'EOF'
content_filter = scan:[127.0.0.1]:10025
receive_override_options = no_address_mappings
EOF

# Add to master.cf
cat >> /etc/postfix/master.cf << 'EOF'

# Virus scanning
scan      unix  -       -       n       -       16      smtp
        -o smtp_data_done_timeout=1200
        -o smtp_send_xforward_command=yes
        -o disable_dns_lookups=yes
        -o max_use=20

127.0.0.1:10026 inet  n       -       n       -       16      smtpd
        -o content_filter=
        -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks
        -o smtpd_restriction_classes=
        -o smtpd_client_restrictions=
        -o smtpd_helo_restrictions=
        -o smtpd_sender_restrictions=
        -o smtpd_recipient_restrictions=permit_mynetworks,reject
        -o mynetworks_style=host
        -o strict_rfc821_envelopes=yes
EOF

Webmail Installation

Step 1: Install Roundcube

# Install dependencies
apk add nginx php82 php82-fpm php82-imap php82-ldap php82-pdo_mysql \
    php82-session php82-dom php82-xml php82-json php82-openssl \
    php82-mbstring php82-intl php82-zip

# Download Roundcube
cd /tmp
wget https://github.com/roundcube/roundcubemail/releases/download/1.6.3/roundcubemail-1.6.3-complete.tar.gz
tar -xzf roundcubemail-1.6.3-complete.tar.gz

# Install Roundcube
mv roundcubemail-1.6.3 /var/www/roundcube
chown -R nginx:nginx /var/www/roundcube

Step 2: Configure Roundcube

# Create database
mysql -u root -p << 'EOF'
CREATE DATABASE roundcube;
CREATE USER 'roundcube'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON roundcube.* TO 'roundcube'@'localhost';
FLUSH PRIVILEGES;
EOF

# Configure Roundcube
cat > /var/www/roundcube/config/config.inc.php << 'EOF'
<?php
$config['db_dsnw'] = 'mysql://roundcube:password@localhost/roundcube';
$config['default_host'] = 'localhost';
$config['default_port'] = 143;
$config['smtp_server'] = 'localhost';
$config['smtp_port'] = 25;
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';
$config['support_url'] = '';
$config['product_name'] = 'Webmail';
$config['des_key'] = 'your-24-char-random-key';
$config['plugins'] = array('archive', 'zipdownload');
$config['language'] = 'en_US';
$config['enable_spellcheck'] = true;
$config['mail_domain'] = '%d';
?>
EOF

# Configure Nginx
cat > /etc/nginx/conf.d/roundcube.conf << 'EOF'
server {
    listen 80;
    server_name webmail.example.com;
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl http2;
    server_name webmail.example.com;
    
    ssl_certificate /etc/ssl/certs/mail.crt;
    ssl_certificate_key /etc/ssl/private/mail.key;
    
    root /var/www/roundcube;
    index index.php;
    
    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }
    
    location ~ \.php$ {
        fastcgi_pass unix:/run/php-fpm82.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }
    
    location ~ /\. {
        deny all;
    }
}
EOF

Email Client Configuration

Step 1: Thunderbird Configuration

# Create autoconfiguration
mkdir -p /var/www/autoconfig/mail
cat > /var/www/autoconfig/mail/config-v1.1.xml << 'EOF'
<?xml version="1.0" encoding="UTF-8"?>
<clientConfig version="1.1">
    <emailProvider id="example.com">
        <domain>example.com</domain>
        <displayName>Example Mail</displayName>
        <displayShortName>Example</displayShortName>
        <incomingServer type="imap">
            <hostname>mail.example.com</hostname>
            <port>993</port>
            <socketType>SSL</socketType>
            <authentication>password-cleartext</authentication>
            <username>%EMAILADDRESS%</username>
        </incomingServer>
        <incomingServer type="pop3">
            <hostname>mail.example.com</hostname>
            <port>995</port>
            <socketType>SSL</socketType>
            <authentication>password-cleartext</authentication>
            <username>%EMAILADDRESS%</username>
        </incomingServer>
        <outgoingServer type="smtp">
            <hostname>mail.example.com</hostname>
            <port>465</port>
            <socketType>SSL</socketType>
            <authentication>password-cleartext</authentication>
            <username>%EMAILADDRESS%</username>
        </outgoingServer>
    </emailProvider>
</clientConfig>
EOF

Step 2: Mobile Device Setup Script

# Create mobile configuration profile generator
cat > /usr/local/bin/generate-mail-profile << 'EOF'
#!/bin/sh
# Generate mail configuration profile

EMAIL=$1
DOMAIN=$(echo $EMAIL | cut -d@ -f2)
UUID1=$(uuidgen)
UUID2=$(uuidgen)
UUID3=$(uuidgen)

cat << XML
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>PayloadContent</key>
    <array>
        <dict>
            <key>EmailAccountDescription</key>
            <string>$EMAIL</string>
            <key>EmailAccountType</key>
            <string>EmailTypeIMAP</string>
            <key>EmailAddress</key>
            <string>$EMAIL</string>
            <key>IncomingMailServerAuthentication</key>
            <string>EmailAuthPassword</string>
            <key>IncomingMailServerHostName</key>
            <string>mail.$DOMAIN</string>
            <key>IncomingMailServerPortNumber</key>
            <integer>993</integer>
            <key>IncomingMailServerUseSSL</key>
            <true/>
            <key>IncomingMailServerUsername</key>
            <string>$EMAIL</string>
            <key>OutgoingMailServerAuthentication</key>
            <string>EmailAuthPassword</string>
            <key>OutgoingMailServerHostName</key>
            <string>mail.$DOMAIN</string>
            <key>OutgoingMailServerPortNumber</key>
            <integer>465</integer>
            <key>OutgoingMailServerUseSSL</key>
            <true/>
            <key>OutgoingMailServerUsername</key>
            <string>$EMAIL</string>
            <key>PayloadDescription</key>
            <string>Configures email account</string>
            <key>PayloadDisplayName</key>
            <string>$EMAIL</string>
            <key>PayloadIdentifier</key>
            <string>com.example.mail.$UUID1</string>
            <key>PayloadType</key>
            <string>com.apple.mail.managed</string>
            <key>PayloadUUID</key>
            <string>$UUID2</string>
            <key>PayloadVersion</key>
            <integer>1</integer>
        </dict>
    </array>
    <key>PayloadDisplayName</key>
    <string>Mail Configuration</string>
    <key>PayloadIdentifier</key>
    <string>com.example.mail</string>
    <key>PayloadType</key>
    <string>Configuration</string>
    <key>PayloadUUID</key>
    <string>$UUID3</string>
    <key>PayloadVersion</key>
    <integer>1</integer>
</dict>
</plist>
XML
EOF

chmod +x /usr/local/bin/generate-mail-profile

Application Integration

Step 1: PHP Mail Integration

# Create PHP mail configuration
cat > /var/www/html/mail-test.php << 'EOF'
<?php
// SMTP configuration
ini_set('SMTP', 'localhost');
ini_set('smtp_port', '25');
ini_set('sendmail_from', '[email protected]');

// Using PHPMailer (recommended)
require 'vendor/autoload.php';

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

$mail = new PHPMailer(true);

try {
    // Server settings
    $mail->isSMTP();
    $mail->Host       = 'localhost';
    $mail->SMTPAuth   = true;
    $mail->Username   = '[email protected]';
    $mail->Password   = 'password';
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Port       = 587;

    // Recipients
    $mail->setFrom('[email protected]', 'Mailer');
    $mail->addAddress('[email protected]', 'Joe User');

    // Content
    $mail->isHTML(true);
    $mail->Subject = 'Test Email';
    $mail->Body    = 'This is a test email body';
    $mail->AltBody = 'This is the plain text version';

    $mail->send();
    echo 'Message has been sent';
} catch (Exception $e) {
    echo "Message could not be sent. Error: {$mail->ErrorInfo}";
}
?>
EOF

Step 2: Python Mail Integration

# Create Python mail script
cat > /usr/local/bin/send-mail.py << 'EOF'
#!/usr/bin/env python3
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase
from email import encoders
import os

def send_email(subject, body, to_email, from_email="[email protected]", 
                smtp_server="localhost", smtp_port=587, 
                username=None, password=None, attachment=None):
    """Send email with optional attachment"""
    
    # Create message
    msg = MIMEMultipart()
    msg['From'] = from_email
    msg['To'] = to_email
    msg['Subject'] = subject
    
    # Add body
    msg.attach(MIMEText(body, 'plain'))
    
    # Add attachment if provided
    if attachment and os.path.isfile(attachment):
        with open(attachment, "rb") as f:
            part = MIMEBase('application', 'octet-stream')
            part.set_payload(f.read())
            encoders.encode_base64(part)
            part.add_header(
                'Content-Disposition',
                f'attachment; filename= {os.path.basename(attachment)}'
            )
            msg.attach(part)
    
    # Send email
    try:
        server = smtplib.SMTP(smtp_server, smtp_port)
        server.starttls()
        
        if username and password:
            server.login(username, password)
        
        text = msg.as_string()
        server.sendmail(from_email, to_email, text)
        server.quit()
        
        return True, "Email sent successfully"
    except Exception as e:
        return False, str(e)

# Example usage
if __name__ == "__main__":
    success, message = send_email(
        subject="Test Email",
        body="This is a test email from Python",
        to_email="[email protected]",
        username="[email protected]",
        password="password"
    )
    print(message)
EOF

chmod +x /usr/local/bin/send-mail.py

Step 3: System Notification Integration

# Create system notification script
cat > /usr/local/bin/notify-admin << 'EOF'
#!/bin/sh
# Send system notifications via email

SUBJECT="$1"
MESSAGE="$2"
PRIORITY="${3:-normal}"
ADMIN_EMAIL="[email protected]"

# Add priority header
case "$PRIORITY" in
    high)
        HEADERS="X-Priority: 1\nImportance: High"
        ;;
    low)
        HEADERS="X-Priority: 5\nImportance: Low"
        ;;
    *)
        HEADERS="X-Priority: 3"
        ;;
esac

# Send notification
echo -e "$HEADERS\n\n$MESSAGE" | mail -s "[$HOSTNAME] $SUBJECT" "$ADMIN_EMAIL"

# Log notification
echo "$(date): Notification sent - $SUBJECT" >> /var/log/notifications.log
EOF

chmod +x /usr/local/bin/notify-admin

# Create cron job for system alerts
cat > /etc/periodic/hourly/system-alerts << 'EOF'
#!/bin/sh
# Check system status and send alerts

# Check disk space
DISK_USAGE=$(df -h / | awk 'NR==2 {print $5}' | sed 's/%//')
if [ $DISK_USAGE -gt 90 ]; then
    /usr/local/bin/notify-admin "Disk Space Alert" "Root partition is $DISK_USAGE% full" "high"
fi

# Check mail queue
QUEUE_SIZE=$(mailq | grep -c "^[A-F0-9]")
if [ $QUEUE_SIZE -gt 100 ]; then
    /usr/local/bin/notify-admin "Mail Queue Alert" "Mail queue has $QUEUE_SIZE messages" "high"
fi

# Check services
for service in postfix dovecot; do
    if ! rc-service $service status >/dev/null 2>&1; then
        /usr/local/bin/notify-admin "Service Alert" "$service is not running" "high"
    fi
done
EOF

chmod +x /etc/periodic/hourly/system-alerts

Monitoring and Logging

Step 1: Mail Log Analysis

# Install log analysis tools
apk add pflogsumm

# Create log analysis script
cat > /usr/local/bin/mail-stats << 'EOF'
#!/bin/sh
# Generate mail statistics

LOG_FILE="/var/log/mail.log"
OUTPUT_FILE="/var/log/mail-stats-$(date +%Y%m%d).txt"

echo "Mail Statistics Report - $(date)" > "$OUTPUT_FILE"
echo "======================================" >> "$OUTPUT_FILE"

# General statistics
pflogsumm -d today "$LOG_FILE" >> "$OUTPUT_FILE"

# Top senders
echo -e "\nTop Senders:" >> "$OUTPUT_FILE"
grep "from=<" "$LOG_FILE" | awk '{print $7}' | sort | uniq -c | sort -rn | head -10 >> "$OUTPUT_FILE"

# Top recipients
echo -e "\nTop Recipients:" >> "$OUTPUT_FILE"
grep "to=<" "$LOG_FILE" | awk '{print $7}' | sort | uniq -c | sort -rn | head -10 >> "$OUTPUT_FILE"

# Rejected connections
echo -e "\nRejected Connections:" >> "$OUTPUT_FILE"
grep "NOQUEUE: reject" "$LOG_FILE" | wc -l >> "$OUTPUT_FILE"

# Send report
cat "$OUTPUT_FILE" | mail -s "Daily Mail Statistics" [email protected]
EOF

chmod +x /usr/local/bin/mail-stats

# Add to cron
echo "0 23 * * * /usr/local/bin/mail-stats" >> /etc/crontabs/root

Step 2: Real-time Monitoring

# Create monitoring dashboard script
cat > /usr/local/bin/mail-monitor << 'EOF'
#!/bin/sh
# Real-time mail server monitoring

clear
while true; do
    echo "=== Mail Server Monitor - $(date) ==="
    echo
    
    # Queue status
    echo "Mail Queue:"
    mailq | tail -5
    echo
    
    # Active connections
    echo "Active Connections:"
    netstat -tan | grep -E ':25|:143|:993|:110|:995' | grep ESTABLISHED | wc -l
    echo
    
    # Recent logs
    echo "Recent Activity:"
    tail -5 /var/log/mail.log
    echo
    
    # Service status
    echo "Service Status:"
    for service in postfix dovecot spamd clamd; do
        printf "%-10s: " "$service"
        if rc-service $service status >/dev/null 2>&1; then
            echo "Running"
        else
            echo "Stopped"
        fi
    done
    
    sleep 5
    clear
done
EOF

chmod +x /usr/local/bin/mail-monitor

Backup and Migration

Step 1: Backup Script

# Create comprehensive backup script
cat > /usr/local/bin/backup-mail << 'EOF'
#!/bin/sh
# Backup mail server configuration and data

BACKUP_DIR="/backup/mail"
DATE=$(date +%Y%m%d_%H%M%S)
BACKUP_FILE="$BACKUP_DIR/mail-backup-$DATE.tar.gz"

# Create backup directory
mkdir -p "$BACKUP_DIR"

# Create temporary directory
TEMP_DIR=$(mktemp -d)
mkdir -p "$TEMP_DIR"/{config,data,databases}

# Backup configurations
cp -r /etc/postfix "$TEMP_DIR/config/"
cp -r /etc/dovecot "$TEMP_DIR/config/"
cp -r /etc/mail/spamassassin "$TEMP_DIR/config/"
cp -r /etc/clamav "$TEMP_DIR/config/"

# Backup mail data
rsync -a /var/mail/ "$TEMP_DIR/data/mail/"
rsync -a /var/spool/mail/ "$TEMP_DIR/data/spool/"

# Backup databases
if command -v mysqldump >/dev/null; then
    mysqldump roundcube > "$TEMP_DIR/databases/roundcube.sql"
fi

# Backup user list
getent passwd | grep -E "^[^:]+:[^:]+:[0-9]{4,}" > "$TEMP_DIR/users.txt"

# Create archive
tar -czf "$BACKUP_FILE" -C "$TEMP_DIR" .

# Cleanup
rm -rf "$TEMP_DIR"

# Report
echo "Backup completed: $BACKUP_FILE"
ls -lh "$BACKUP_FILE"

# Rotate old backups (keep last 7)
find "$BACKUP_DIR" -name "mail-backup-*.tar.gz" -mtime +7 -delete
EOF

chmod +x /usr/local/bin/backup-mail

# Add to cron
echo "0 2 * * * /usr/local/bin/backup-mail" >> /etc/crontabs/root

Step 2: Migration Script

# Create migration script
cat > /usr/local/bin/migrate-mail << 'EOF'
#!/bin/sh
# Migrate mail from another server

SOURCE_SERVER=$1
SOURCE_USER=${2:-root}

if [ -z "$SOURCE_SERVER" ]; then
    echo "Usage: $0 <source-server> [username]"
    exit 1
fi

echo "Starting mail migration from $SOURCE_SERVER"

# Sync mail data
echo "Syncing mail data..."
rsync -avz --progress \
    "$SOURCE_USER@$SOURCE_SERVER:/var/mail/" \
    /var/mail/

# Sync configurations
echo "Syncing configurations..."
rsync -avz \
    "$SOURCE_USER@$SOURCE_SERVER:/etc/postfix/" \
    /etc/postfix.migrated/

rsync -avz \
    "$SOURCE_USER@$SOURCE_SERVER:/etc/dovecot/" \
    /etc/dovecot.migrated/

# Sync user accounts
echo "Syncing user accounts..."
ssh "$SOURCE_USER@$SOURCE_SERVER" "getent passwd" > /tmp/remote-users.txt

# Import users
while IFS=: read -r username x uid gid gecos home shell; do
    if [ $uid -ge 1000 ] && [ $uid -lt 65534 ]; then
        if ! id "$username" >/dev/null 2>&1; then
            useradd -u "$uid" -g "$gid" -d "$home" -s "$shell" -c "$gecos" "$username"
            echo "Imported user: $username"
        fi
    fi
done < /tmp/remote-users.txt

echo "Migration completed"
echo "Please review and merge configuration files manually"
EOF

chmod +x /usr/local/bin/migrate-mail

Troubleshooting

Common Issues

1. Mail not being delivered:

# Check mail queue
mailq

# View mail log
tail -f /var/log/mail.log

# Test mail delivery
echo "Test" | mail -s "Test" [email protected]

# Check DNS
dig MX example.com

2. Authentication failures:

# Test SASL authentication
testsaslauthd -u username -p password

# Check Dovecot auth
doveadm auth test [email protected]

# Debug authentication
tail -f /var/log/dovecot.log | grep auth

3. SSL/TLS issues:

# Test SSL certificate
openssl s_client -connect mail.example.com:993 -servername mail.example.com

# Check certificate expiry
openssl x509 -in /etc/ssl/certs/mail.crt -noout -dates

# Test STARTTLS
openssl s_client -starttls smtp -connect mail.example.com:587

Debug Mode

# Enable Postfix debug
postconf -e "debug_peer_list = 127.0.0.1"
postconf -e "debug_peer_level = 3"

# Enable Dovecot debug
cat >> /etc/dovecot/dovecot.conf << 'EOF'
auth_debug = yes
mail_debug = yes
verbose_ssl = yes
EOF

# Restart services
rc-service postfix reload
rc-service dovecot reload

Best Practices

Security Hardening

# Create security checklist script
cat > /usr/local/bin/mail-security-check << 'EOF'
#!/bin/sh
# Mail server security audit

echo "Mail Server Security Audit"
echo "========================="

# Check open relay
echo -n "Open relay test: "
if postconf | grep -q "mynetworks = 127.0.0.0/8"; then
    echo "PASS"
else
    echo "WARNING - Check mynetworks setting"
fi

# Check authentication
echo -n "SASL authentication: "
if postconf | grep -q "smtpd_sasl_auth_enable = yes"; then
    echo "ENABLED"
else
    echo "DISABLED"
fi

# Check TLS
echo -n "TLS encryption: "
if postconf | grep -q "smtpd_use_tls = yes"; then
    echo "ENABLED"
else
    echo "DISABLED"
fi

# Check RBL
echo -n "RBL checking: "
if postconf | grep -q "reject_rbl_client"; then
    echo "ENABLED"
else
    echo "DISABLED"
fi

# Check SPF
echo -n "SPF record: "
if dig TXT example.com | grep -q "v=spf1"; then
    echo "CONFIGURED"
else
    echo "MISSING"
fi

# Check DKIM
echo -n "DKIM signing: "
if [ -f /etc/opendkim/keys/*/default.private ]; then
    echo "CONFIGURED"
else
    echo "NOT CONFIGURED"
fi
EOF

chmod +x /usr/local/bin/mail-security-check

Performance Tuning

# Create performance tuning script
cat > /usr/local/bin/tune-mail-performance << 'EOF'
#!/bin/sh
# Optimize mail server performance

# Postfix tuning
postconf -e "default_process_limit = 100"
postconf -e "qmgr_message_active_limit = 20000"
postconf -e "qmgr_message_recipient_limit = 20000"
postconf -e "smtp_connection_cache_destinations = $mydestination"
postconf -e "smtp_connection_cache_on_demand = yes"
postconf -e "smtp_connection_cache_time_limit = 2s"

# Dovecot tuning
cat >> /etc/dovecot/conf.d/10-performance.conf << EOC
# Performance optimizations
mail_fsync = optimized
mail_nfs_storage = no
mail_nfs_index = no
mmap_disable = no
mail_cache_min_mail_count = 10
maildir_copy_with_hardlinks = yes

# Process limits
default_process_limit = 200
default_client_limit = 1000

# Login process
login_max_processes_count = 128
login_max_connections = 256

# Mail process
mail_max_userip_connections = 50
EOC

echo "Performance tuning applied"
echo "Restart services to apply changes"
EOF

chmod +x /usr/local/bin/tune-mail-performance

Conclusion

You’ve successfully configured a complete email integration system on Alpine Linux. This setup includes a full-featured mail server with SMTP, IMAP, and POP3 support, along with spam filtering, virus scanning, webmail access, and comprehensive monitoring. Your email infrastructure is now ready to handle both sending and receiving mail securely and efficiently.

Remember to regularly update your mail server components, monitor logs for suspicious activity, and maintain proper backups. With this configuration, you have a professional-grade email system suitable for production use.