Grommunio Mail Server

This tutorial covers the steps to set up a mail server on Alpine Linux using grommunio, an open-source groupware solution that supports email, calendar, and task management. Grommunio stands out with its unique MAPI support, enabling seamless integration with Microsoft Outlook and other MAPI clients, making it an ideal choice for open-source alternatives to proprietary systems. The setup includes essential components like MariaDB, Nginx, PHP, and Postfix to create a fully functional mail server. Follow along to build a secure, scalable communication platform using grommunio's powerful features.

Prerequisites

Before proceeding with the installation, ensure you have a fresh Alpine Linux system setup. You'll need root privileges to execute these commands.

Procedure

1. Install and configure MariaDB
2. MariaDB performance tuning (optional)
3. Install and configure Nginx
4. Install and configure PHP
5. Install and configure Postfix
6. Install and configure Grommunio
7. Configure Valkey (Redis replacement)
8. Install and configure Rspamd
9. Finalize and verify installation

1. Install and Configure MariaDB

Install MariaDB

To start, install MariaDB and necessary utilities

apk add mariadb mariadb-client mariadb-server-utils

Define the variables used later in the setup setup and configuration.

The default datapath is `/var/lib/mysql` and contains the entire database. If you prefer another location define it here and create a symlink. In any case, the grommunio database will be rather small as it only contains the configuration.

DB_DATA_PATH="/srv/mysql"
DB_ROOT_PASS="Passw0rd1"
DB_USER="admin"
DB_PASS="Passw0rd2"

Setup the default system tables:

sudo mysql_install_db --user=mysql --datadir=${DB_DATA_PATH}

Set a symlink to the standard mysql data directory for compatibility reason:

ln -s /srv/mysql /var/lib/mysql

Restart service:

rc-service mariadb restart

Run the built-in security script:

Set the new root password to the one defined above and answer everything with 'y'

sudo mysql_secure_installation

Create MariaDB User

Create a new user for Grommunio and assign privileges:

echo "GRANT ALL ON *.* TO ${DB_USER}@'127.0.0.1' IDENTIFIED BY '${DB_PASS}' WITH GRANT OPTION;" > /tmp/sql
echo "GRANT ALL ON *.* TO ${DB_USER}@'localhost' IDENTIFIED BY '${DB_PASS}' WITH GRANT OPTION;" >> /tmp/sql
echo "GRANT ALL ON *.* TO ${DB_USER}@'::1' IDENTIFIED BY '${DB_PASS}' WITH GRANT OPTION;" >> /tmp/sql
echo "DELETE FROM mysql.user WHERE User=;" >> /tmp/sql
echo "FLUSH PRIVILEGES;" >> /tmp/sql
cat /tmp/sql | mysql -u root --password="${DB_ROOT_PASS}"

Configure MariaDB

Edit the MariaDB configuration for better performance:

vi /etc/my.cnf.d/mariadb-server.cnf

Add the following configuration:

[mysqld]
#skip-networking

## Configuration for grommunio (most values are default)
innodb_log_buffer_size=16M
innodb_log_file_size=32M
innodb_read_io_threads=4
innodb_write_io_threads=4

join_buffer_size=512K
query_cache_size=0
query_cache_type=0
query_cache_limit=2M

# Activate performance schema
performance_schema=ON

# Bind to localhost only
bind-address = 127.0.0.1

# Disable DNS lookups as we only use localhost connections
skip-name-resolve=ON

Create a default charset configuration for MariaDB:

cat > /etc/my.cnf.d/mariadb-server-default-charset.cnf << EOF
[client]
default-character-set = utf8mb4

[mysqld]
collation_server = utf8mb4_general_ci
character_set_server = utf8mb4

[mysql]
default-character-set = utf8mb4
EOF

Restart MariaDB and enable it to start on boot:

rc-update add mariadb default
rc-service mariadb restart

Verify MariaDB Setup

Check if the MariaDB listener is running and bound to the correct interface (127.0.0.1):

ss -tulpn

Create Grommunio Database

Define the database parameters and create the Grommunio database:

MYSQL_HOST="localhost"
MYSQL_USER="grommunio"
MYSQL_PASS="Passw0rd3"
MYSQL_DB="grommunio"

echo "create database $MYSQL_DB character set 'utf8mb4';" > /tmp/sql
echo "grant select, insert, update, delete, create, drop, index, alter, create temporary tables, lock tables on $MYSQL_DB.* TO $MYSQL_USER@$MYSQL_HOST identified by '$MYSQL_PASS';" >> /tmp/sql
echo "flush privileges;" >> /tmp/sql
cat /tmp/sql | mysql -u admin --password="${DB_PASS}"

Test the database connection:

mysql -hlocalhost -u grommunio -p${MYSQL_PASS} grommunio

2. MariaDB Performance Tuning (Optional)

To assist us in checking and tuning the configuration as per our specific needs, we can install mysqltuner, a script that will provide suggestions to improve the performance of our database server and increase its stability

Download MySQLTuner

wget -v https://raw.githubusercontent.com/major/MySQLTuner-perl/master/mysqltuner.pl -O /tmp/mysqltuner.pl

Move it to the correct directory and set permissions:

mv /tmp/mysqltuner.pl /usr/local/bin/mysqltuner.pl
chmod 755 /usr/local/bin/mysqltuner.pl

Install perl

NOTE: The perl-doc package is installed because it's the only one containing the perldiag.pod required by mysqltuner.pl

apk add perl perl-doc

Execute the script

You will be prompted to enter the credentials of your administrative MariaDB account:

/usr/local/bin/mysqltuner.pl --user admin --pass ${DB_PASS}

3. Install and Configure Nginx

Install Nginx

Install the necessary Nginx modules:

apk add nginx nginx-mod-http-headers-more nginx-mod-http-vts nginx-mod-http-brotli

Configure Nginx

Backup the original Nginx configuration and edit it for security headers and TLS settings:

cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.orig
vi /etc/nginx/nginx.conf

Add the following configuration:

#error_log /var/log/nginx/error.log warn;
error_log syslog:server=unix:/dev/log,facility=local2,nohostname warn;

### Common headers for security
# TODO: Set temporary to a lower value until we are sure it's working
#more_set_headers "Strict-Transport-Security : max-age=15768000; includeSubDomains; preload";
more_set_headers "Strict-Transport-Security : max-age=2592000; includeSubDomains;";
more_set_headers "X-Frame-Options : SAMEORIGIN";
more_set_headers "Content-Security-Policy : default-src https: data: 'unsafe-inline' 'unsafe-eval' always";
more_set_headers "X-Xss-Protection : 1; mode=block";
more_set_headers "X-Content-Type-Options : nosniff";
more_set_headers "Referrer-Policy : strict-origin-when-cross-origin";
more_set_headers "Server : Follow the white rabbit.";

### TLS settings
ssl_protocols TLSv1.2 TLSv1.3;
ssl_session_cache shared:SSL:1m;
ssl_session_timeout 5m;

log_format main_ssl '$remote_addr - $remote_user [$time_local] "$request" '
        '$status $body_bytes_sent "$http_referer" '
        '"$http_user_agent" "$http_x_forwarded_for" '
        'client_ciphers="$ssl_ciphers" client_curves="$ssl_curves"';

#access_log /var/log/nginx/access.log main_ssl; # Disabled for performance
#access_log syslog:server=unix:/dev/log,facility=local2,nohostname main; # Disabled for performance
access_log off;

Disable the default page by renaming it:

mv /etc/nginx/http.d/default.conf /etc/nginx/http.d/default.orig

Restart Nginx and enable it to start on boot:

rc-update add nginx
rc-service nginx restart

4. Install and Configure PHP

Install PHP

Install the basic php packages. The modules are installed as grommunio dependencies:

apk add php83 php83-fpm

Disable default fpm conf:

mv /etc/php83/php-fpm.d/www.conf /etc/php83/php-fpm.d/www.conf.default

Harden PHP Configuration

Backup config file /etc/php83/php.ini

cp /etc/php83/php.ini /etc/php83/php-fpm.d/php.ini.orig

Disable remote PHP code execution:

sed 's/^;\?\(allow_url_fopen\).*/\1 = Off/' -i /etc/php83/php.ini 
sed 's/^;\?\(allow_url_include\).*/\1 = Off/' -i /etc/php83/php.ini 

Disable information leakage:

sed 's/^;\?\(expose_php\).*/\1 = Off/' -i /etc/php83/php.ini 

Configure Error handling:

sed 's/^;\?\(display_errors\).*/\1 = Off/' -i /etc/php83/php.ini 
sed 's/^;\?\(display_startup_errors\).*/\1 = Off/' -i /etc/php83/php.ini 
sed 's/^;\?\(log_errors\).*/\1 = On/' -i /etc/php83/php.ini 
sed 's/^;\?\(error_log = syslog\).*/\1/' -i /etc/php83/php.ini 

PHP Resource Control (Optional):

#sed 's/^\(max_execution_time\).*/\1 = 25/' -i /etc/php83/php.ini 
#sed 's/^\(max_input_time\).*/\1 = 25/' -i /etc/php83/php.ini 
#sed 's/^\(memory_limit\).*/\1 = 30M/' -i /etc/php83/php.ini 
#sed 's/^\(post_max_size\).*/\1 = 1M/' -i /etc/php83/php.ini 
#sed 's/^;\?\(max_input_vars\).*/\1 = 1000/' -i /etc/php83/php.ini 

Disable vulnerable functions:

sed 's/^\(disable_functions\).*/\1 = apache_note, apache_setenv, chgrp, curl_multi_exec, define_sys, define_syslog_variables, debugger_off, debugger_on, diskfreespace, _getppid, escapeshellarg, escapeshellcmd, exec, getmyuid, ini_restore, leak, listen, parse_ini_file, passthru, pcntl_alarm, pcntl_async_signals, pcntl_exec, pcntl_fork, pcntl_get_last_error, pcntl_getpriority, pcntl_setpriority, pcntl_signal, pcntl_signal_dispatch, pcntl_signal_get_handler, pcntl_sigprocmask, pcntl_sigtimedwait, pcntl_sigwaitinfo, pcntl_strerror, pcntl_unshare, pcntl_wait, pcntl_waitpid, pcntl_wexitstatus, pcntl_wifcontinued, pcntl_wifexited, pcntl_wifsignaled, pcntl_wifstopped, pcntl_wstopsig, pcntl_wtermsig, posix, posix_ctermid, posix_getcwd, posix_getegid, posix_geteuid, posix_getgid, posix_getgrgid, posix_getgrnam, posix_getgroups, posix_getlogin, posix_getpgid, posix_getpgrp, posix_getpid, posix_getpwnam, posix_getpwuid, posix_getrlimit, posix_getsid, posix_isatty, posix_kill, posix_mkfifo, posix_setegid, posix_seteuid, posix_setgid, posix_setpgid, posix_setsid, posix_setuid, posix_times, posix_ttyname, posix_uname, popen, proc_close, proc_get_status, proc_nice, proc_open, proc_terminate, shell_exec, show_source, system, url_exec/' -i /etc/php83/php.ini 

Harden Session Security:

sed 's/^;\?\(session.use_strict_mode\).*/\1 = 1/' -i /etc/php83/php.ini 
sed 's/^;\?\(session.use_cookies\).*/\1 = 1/' -i /etc/php83/php.ini 
sed 's/^;\?\(session.cookie_secure\).*/\1 = 1/' -i /etc/php83/php.ini 
sed 's/^;\?\(session.use_only_cookies\).*/\1 = 1/' -i /etc/php83/php.ini 
sed 's/^;\?\(session.cookie_httponly\).*/\1 = 1/' -i /etc/php83/php.ini

5. Install and Configure Postfix

Install Postfix

Install the required packages:

apk add postfix postfix-mysql postfix-pcre

Configure Postfix

First backup the original files:

mv /etc/postfix/main.cf /etc/postfix/main.cf.orig
mv /etc/postfix/master.cf /etc/postfix/master.cf.orig
mv /etc/postfix/header_checks /etc/postfix/header_checks.orig

Download the prepared configuration files:

wget https://alpinelinuxsupport.com/downloads/postfix-configuration-files.zip

Copy the prepared configuration files to `/etc/postfix/` and adapt the configuration to your environment. Ensure you change at least the following values:

main.cf: myhostname, mynetworks, smtp_tls_chain_files, smtpd_tls_chain_files, local_recipient_maps, mydestination, 
        virtual_*, relayhost, mua_sender_restrictions, smtpd_recipient_restrictions
master.cf: smtpd_tls_chain_files=/etc/ssl/private/internal-server-key-and-cert.pem

Create the required postmap files:

newaliases
postmap /etc/postfix/transport

Run Postfix setup:

newaliases
postmap /etc/postfix/transport

Enable the postfix service and restart:

rc-update add postfix
rc-service postfix restart

Verify Postfix Logs

Check the Postfix logs for any errors:

tail -f /var/log/maillog

6. Install and Configure Grommunio

Enable IPv6

First of all, turn on ipv6 which is mandatory for grommunio daemons

Edit `/etc/hosts` to include IPv6 localhost:

vi /etc/hosts
-----
::1		localhost ipv6-localhost ipv6-loopback

Ensure IPv6 is enabled in `/etc/sysctl.conf`:

sed -i 's/^net\.ipv6\.conf\..*\.disable_ipv6\s=\s1/#&/' /etc/sysctl.conf
sysctl -p
ping ::1  # Test if IPv6 is working

Specify Database Parameters

Specify DB parameters if necessary (already specified above in step 1)

MYSQL_HOST="localhost"
MYSQL_USER="grommunio"
MYSQL_PASS="Passw0rd3"
MYSQL_DB="grommunio"

Specify Domain Parameters

The FQDN is for example used by Outlook clients to connect. This name will have to be present in the used certificate.

The default Mail Domain is for example used for Non-Delivery Reports and for generation of some simple TLS certificates. Specify ONLY ONE domain here.

Adjust the following for your specific setup:

FQDN="mail.example.local"
MAILDOMAIN="example.com"
RELAYHOST="123.123.123.1"
ADMIN_PASS="Passw0rd4"

Install Packages

Install necessary dependencies (util-linux-login is required to get pam.d working):

apk add valkey valkey-cli cyrus-sasl cyrus-sasl-login util-linux-login

Install grommunio packages:

apk add grommunio-gromox grommunio-web grommunio-admin-api grommunio-admin-web grommunio-index grommunio-error-pages

Optionally, install deprecated ActiveSync if needed:

apk add grommunio-dav grommunio-sync

Relocate Mail Storage

The directory `/var/lib/gromox` will be the largest directory containing all the mails and attachments. We therefore relocate it to another disk and create a symlink:

mv /var/lib/gromox /srv/gromox
ln -s /srv/gromox /var/lib/gromox

Enable Required Services

Enable all required services:

rc-update add grommunio-admin-api
rc-update add gromox-delivery
rc-update add gromox-delivery-queue
rc-update add gromox-event
rc-update add gromox-http
rc-update add gromox-imap
rc-update add gromox-midb
rc-update add gromox-pop3
rc-update add gromox-timer
rc-update add gromox-zcore
rc-update add valkey@grommunio
rc-update add php-fpm83 
rc-update add saslauthd

Configure Grommunio

Modify the configuration files with the custom parameters specified above.

Configure gromox *.cfg:

sed -i "s/mail.example.local/${FQDN}/g" /etc/gromox/*.cfg
sed -i "s/example.com/${MAILDOMAIN}/g" /etc/gromox/*.cfg

Configure gromox adaptor:

sed -i "s/<password>/${MYSQL_PASS}/g" /etc/gromox/mysql_adaptor.cfg
cat /etc/gromox/mysql_adaptor.cfg

Configure autodiscovery:

sed -i "s/mail.example.local/${FQDN}/g" /etc/gromox/autodiscover.ini
sed -i "s/<password>/${MYSQL_PASS}/g" /etc/gromox/autodiscover.ini
cat /etc/gromox/autodiscover.ini

Prepare additional postfix file for sender maps:

cp -p /etc/postfix/grommunio-virtual-mailbox-maps.cf /etc/postfix/grommunio-virtual-mailbox-sender-maps.cf
sed -i '/^query =/d' /etc/postfix/grommunio-virtual-mailbox-sender-maps.cf
echo "query = SELECT username FROM users WHERE username='%s' UNION SELECT aliasname FROM aliases WHERE mainname='%s'" >> /etc/postfix/grommunio-virtual-mailbox-sender-maps.cf

Configure postfix files:

sed -i "s/<password>/${MYSQL_PASS}/g" /etc/postfix/grommunio*.cf

Configure TLS certificates:

sed -i "s/mail.example.local/${FQDN}/g" /etc/grommunio-common/nginx/ssl_certificate.conf
sed -i "s/mail.example.local/${FQDN}/g" /etc/grommunio-admin-common/nginx-ssl.conf

Link TLS certificate configuration:

Since both ssl files are identical it might make more sense to link them

ln -s /etc/grommunio-common/nginx/ssl_certificate.conf /etc/grommunio-admin-common/nginx-ssl.conf

Configure grommunio admin:

sed -i "s/mail.example.local/${FQDN}/g" /etc/grommunio-admin-common/config.json
sed -i "s/<password>/${MYSQL_PASS}/g" /etc/grommunio-admin-api/conf.d/database.yaml
cat /etc/grommunio-admin-api/conf.d/database.yaml

Prepare external or self-signed certificate and put them to:

/etc/ssl/certs/${FQDN}.cert.pem
/etc/ssl/private/${FQDN}.key.pem

Concatenate key and cert as needed by postfix:

cat /etc/ssl/private/${FQDN}.key.pem \
    /etc/ssl/certs/${FQDN}.cert.pem \
  > /etc/ssl/private/${FQDN}.key_cert.pem
chmod 640 /etc/ssl/private/*.key_cert.pem
chown root:ssl-cert /etc/ssl/private/*.key_cert.pem
ls -al /etc/ssl/private/

Add gromox to ssl-cert (or another) group allowed to read the private keys:

addgroup gromox ssl-cert

Retrieve the certificate fingerprint:

NOTE: This is only required if you work with a relay server authenticating the client cert.

Add the output to the relay_clientcerts file on the relay server and hash it with the postmap command.

openssl x509 -noout -fingerprint -sha384 -in /etc/ssl/certs/${FQDN}.cert.pem

Configure PAM for SMTP:

mv /etc/pam.d/smtp /etc/pam.d/smtp.orig
cat > /etc/pam.d/smtp <<EOF
#%PAM-1.0
# config for grommunio auth services
auth    required pam_gromox.so service=smtp
account required pam_permit.so
EOF

Configure SASL authentication:

cat > /etc/conf.d/saslauthd <<EOF
# Configuration for /etc/init.d/saslauthd
SASLAUTHD_OPTS="-a pam -r"
EOF

SASL configuration for SMTP service:

mkdir /etc/sasl2
cat > /etc/sasl2/smtpd.conf <<EOF
pwcheck_method: saslauthd
mech_list: plain login
EOF
chmod 600 /etc/sasl2/smtpd.conf

In case you migrate from another server replace X500-org-name with the original one:

X500_ORG_NAME_OLD=$(grep 'x500_org_name=' /etc/gromox/zcore.cfg | cut -d= -f2)
X500_ORG_NAME_NEW=<original-key>
sed -i "s/$X500_ORG_NAME_OLD/$X500_ORG_NAME_NEW/g" /etc/gromox/*

Initialize Database

Initialize the database:

gromox-dbop -C

Set the Grommunio admin password:

grommunio-admin passwd --password "${ADMIN_PASS}"

Add grommunio to the adm group to enable admin UI to read `/var/log/maillog`.

NOTE: Additional custom patch is needed to make the log monitoring work

addgroup grommunio adm

Configure Firewall

Open the necessary firewall ports:

25/tcp
80/tcp
110/tcp
143/tcp
443/tcp
587/tcp
993/tcp
995/tcp
8080/tcp
8443/tcp

7. Configure Valkey

Enable Syslog

The syslog facility is set to 'local0'.

NOTE: It is recommended to redirect local0 to the maillog in syslog.conf as all other grommunio processes write to maillog

vi /etc/valkey/grommunio.conf
-----
#pidfile /var/run/valkey/default.pid
#logfile /var/log/valkey/default.log
syslog-enabled yes
syslog-ident valkey
syslog-facility local0

Enable Memory Overcommit

Add the following sysctl property for valkey

 vi /etc/sysctl.conf
 -----
 # Enable memory overcommit for valkey  
 vm.overcommit_memory = 1

Update the system configuration

sysctl -p

Start Valkey and Test

rcctl restart valkey@grommunio
valkey-cli ping  # Expected result: 'PONG'

8. Install and Configure Rspamd

Install Rspamd

 apk add rspamd rspamd-client

Configure Rspamd

Set general options:

cat > /etc/rspamd/local.d/options.inc <<EOF
dns {
  enable_dnssec = true;
  timeout = 4s;
  retransmits = 5;
}
EOF

Configure redis/valkey connection:

cat > /etc/rspamd/local.d/redis.conf <<EOF
read_servers = "127.0.0.1";
write_servers = "127.0.0.1";
EOF

Configure normal worker:

cat > /etc/rspamd/local.d/worker-normal.inc << EOF
# Normal worker is intended to scan messages for spam
# You might disable normal worker to free up system resources as we use the proxy worker in self-scan mode
enabled = false;
# If the mailer is running on the same host use a unix socket
#bind_socket = "127.0.0.1:11333";
#bind_socket = "/var/run/rspamd/worker-normal.sock mode=0660 owner=rspamd";
EOF

Configure proxy worker:

cat > /etc/rspamd/local.d/worker-proxy.inc << EOF
# Proxy worker is used as postfix milter
# If the mailer is running on the same host use a unix socket
milter = yes;
#bind_socket = "127.0.0.1:11332";
bind_socket = "/var/run/rspamd/worker-proxy.sock mode=0660 owner=rspamd";
timeout = 120s;
upstream "local" {
  default = yes; # Self-scan upstreams are always default
  self_scan = yes; # Enable self-scan
}
count = 4; # Spawn more processes in self-scan mode
EOF

Add postfix to rspamd group to access the socket:

addgroup postfix rspamd

Configure controller worker:

cat > /etc/rspamd/local.d/worker-controller.inc << EOF
# Controller worker is used to manage rspamd stats, to learn rspamd and to serve WebUI
# If the mailer is running on the same host use a unix socket
# NOTE: grommunio connects over http
bind_socket = "127.0.0.1:11334";
#bind_socket = "/var/run/rspamd/worker-controller.sock mode=0660 owner=rspamd";
# password for read-only commands
password = "<encrypted_password_string>";
# password for write commands
enable_password = "<encrypted_password_string>"
secure_ip = "127.0.0.1";
EOF

Create the user password and replace it in worker-controller.inc:

Command: rspamadm pw --encrypt -p P4ssword

sed -i s/\<encrypted_password_string\>/$(rspamadm pw --encrypt -p "${ADMIN_PASS}")/ /etc/rspamd/local.d/worker-controller.inc
cat /etc/rspamd/local.d/worker-controller.inc

Redirect rspamd logs to syslog:

cat > /etc/rspamd/local.d/logging.inc << EOF
# Redirect rspamd logs to the mail log
type = "syslog";
facility = "mail";
level = "notice";
EOF

Configure external relay:

cat > /etc/rspamd/local.d/external_relay.conf << EOF
enabled = true;
rules {
  FETCHMAIL {
    strategy = "local";
  }
}
EOF

Configure actions:

cat > /etc/rspamd/local.d/actions.conf << EOF
reject = 15; # Reject when reaching this score
add_header = 4; # Add spam header when reaching this score
greylist = 3; # Apply greylisting when reaching this score (will emit 'soft reject action')

#rewrite_subject = 6; # Rewrite subject to indicate spam. Cannot be combined with add_header
#unknown_weight = 1.0; # Enable if need to set score for all symbols implicitly
#subject = "***SPAM*** %s"; # Set rewrite subject to this value (%s is replaced by the original subject)
EOF

Configure milter_headers:

cat > /etc/rspamd/local.d/milter_headers.conf << EOF
# Enables x-spamd-result, x-rspamd-server and x-rspamd-queue-id headers (default false)
extended_spam_headers = true;

# Set false to always add headers for local IPs (default true)
skip_local = false;

# Set false to always add headers for authenticated users (default true)
skip_authenticated = false;

# Set false to keep pre-existing spam flag added by an upstream spam filter (default true)
remove_upstream_spam_flag = true;
EOF

Configure dkim signing:

cat > /etc/rspamd/local.d/dkim_signing.conf << EOF
# Enable DKIM signing
enabled = true;

# If false, messages with empty envelope from are not signed
allow_envfrom_empty = true;

# If true, envelope/header domain mismatch is ignored
allow_hdrfrom_mismatch = true;

# If true, multiple from headers are allowed (but only first is used)
allow_hdrfrom_multiple = false;

# If true, username does not need to contain matching domain
allow_username_mismatch = true;

# Default path to key, can include '$domain' and '$selector' variables
path = "/var/lib/rspamd/dkim/\$domain-\$selector.key";

# Default selector to use
selector = "dkim";

# If false, messages from authenticated users are not selected for signing
sign_authenticated = true;

# If false, messages from local networks are not selected for signing
sign_local = false;

# Map file of IP addresses/subnets to consider for signing
#sign_networks = "/some/file"; # or url

# Symbol to add when message is signed
symbol = "DKIM_SIGNED";

# If false, messages from domains not defined here will not be signed
try_fallback = false;

# Domain to use for DKIM signing: can be "header" (MIME From), "envelope" (SMTP From), 
#   "recipient" (SMTP To), "auth" (SMTP username) or directly specified domain name
use_domain = "header";

# Domain to use for DKIM signing when sender is in sign_networks ("header"/"envelope"/"auth")
#use_domain_sign_networks = "header";

# Domain to use for DKIM signing when sender is a local IP ("header"/"envelope"/"auth")
#use_domain_sign_local = "header";

# Whether to normalise domains to eSLD
use_esld = true;

# Whether to get keys from Redis
use_redis = false;

# Hash for DKIM keys in Redis
key_prefix = "DKIM_KEYS";

# map of domains -> names of selectors (since rspamd 1.5.3)
#selector_map = "/etc/rspamd/dkim_selectors.map";

# map of domains -> paths to keys (since rspamd 1.5.3)
#path_map = "/etc/rspamd/dkim_paths.map";

# If `true` get pubkey from DNS record and check if it matches private key
check_pubkey = false;

# Set to `false` if you want to skip signing if public and private keys mismatch
allow_pubkey_mismatch = true;

# Domain specific settings
domain {
  <maildomain> { selector = "<selector>"; }
}
EOF

Specify parameters (MAILDOMAIN already defined above):

MAILDOMAIN="example.com"
SELECTOR="202406"

Replace maildomain and selector in configuration:

sed -i "s/<maildomain>/${MAILDOMAIN}/g" /etc/rspamd/local.d/dkim_signing.conf
sed -i "s/<selector>/${SELECTOR}/g" /etc/rspamd/local.d/dkim_signing.conf

Create DKIM Key Pair:

NOTE: The 'pub' file contains the public key and the configuration to create the corresponding dns record

mkdir -p /var/lib/rspamd/dkim
rspamadm dkim_keygen -s ${SELECTOR} -t ED25519 -d ${MAILDOMAIN} -k /var/lib/rspamd/dkim/${MAILDOMAIN}-${SELECTOR}.key > /var/lib/rspamd/dkim/${MAILDOMAIN}-${SELECTOR}.pub
chown -R rspamd:grommunio /var/lib/rspamd/dkim
chmod 640 /var/lib/rspamd/dkim/${MAILDOMAIN}-${SELECTOR}.key
cat /var/lib/rspamd/dkim/${MAILDOMAIN}-${SELECTOR}.pub

Start Rspamd and Test

 rc-update add rspamd
 rcctl start rspamd

Test rspam client connection getting statistics (you need to wait some minutes until stats are available):

#rspamc -h /run/rspamd/worker-controller.sock stat
rspamc stat

9. Finalize and Verify

Restart Services

Restart all services:

rcctl restart postfix saslauthd rspamd valkey@grommunio nginx php-fpm83 gromox-delivery gromox-event \
    gromox-http gromox-imap gromox-midb gromox-pop3 gromox-delivery-queue gromox-timer gromox-zcore \
    grommunio-admin-api

Verify Service Status

Check the status of all services:

rcctl status

Check Logs

Inspect logs for any errors or issues:

find /var/log -type f | xargs tail -n50 | grep -iE '==>|fail|crit|error|alert|corrupt|warning'

Web UI Access

Admin UI: https://mail.example.local:8443

Web UI: https://mail.example.local

Admin UI - First steps

Log in with user 'admin' and the previously created ADMIN_PASS

Create and change the following entities:

1. Defaults: Set the overall defaults to be applied to all domains and users. If you use PAM, ensure that the flag 'Allow SMTP sending (used by POP3/IMAP clients)' is activated
2. Create an Organization
3. Create a Domain belonging to this organization. Select as well "Create domain admin role"
4. Create Users belonging to the domain

NOTE: For some reason, the first user is not created properly. Permissions are wrong and the sqlite database is not created. It is suggested to create a second user, ensure that the permissions are set correctly and then delete and recreate the first user

Correct user permissions are like follows:

ls -l /var/lib/gromox/user/example.com
drwxrwx---    8 grommuni gromox      4.0K Jun 21 14:05 user1

ls -l /var/lib/gromox/user/example.com/user1
drwxrwx---    8 grommuni gromox      4.0K Jun 21 14:05 .
drwxr-xr-x    4 grommuni gromox      4.0K Jun 21 14:05 ..
drwxrwx---    2 grommuni gromox      4.0K Jun 21 14:05 cid
drwxrwx---    2 grommuni gromox      4.0K Jun 21 14:05 config
drwxrwx---    2 grommuni gromox      4.0K Jun 21 14:05 eml
drwxrwx---    2 grommuni gromox      4.0K Jun 21 14:05 exmdb
drwxrwx---    2 grommuni gromox      4.0K Jun 21 14:05 ext
-rw-r--r--    1 gromox   gromox         0 Jun 21 14:05 tables.sqlite3
drwxrwx---    4 grommuni gromox      4.0K Jun 21 14:05 tmp

Web UI Testing

Verify if you can access the web UI with your new user

Test saslauthd authentication

Finally, test saslauthd authentication with PAM

testsaslauthd -u username -r domain -p password -s smtp
testsaslauthd -u username@domain -p password -s smtp

Add/verify the license

In case you have a license you can configure it in the admin UI under grommunio settings:

https://mail.example.local:8443/license

The default (fallback) community license is defined in the following file

vi /usr/share/grommunio-admin-api/tools/license.py