How to Set Up a Catch-All Email Address with Postfix

How to Set Up a Catch-All Email Address with Postfix

A catch-all email address receives every message sent to your domain that does not match an existing mailbox. This is useful for capturing mistyped addresses, handling legacy aliases, and ensuring no customer correspondence is lost. On your Breeze server running Postfix, setting this up takes just a few configuration changes.

Prerequisites

• A Breeze instance with Postfix installed and configured for your domain
• DNS MX records pointing to your Breeze server
• A dedicated user account to receive the catch-all mail

Step 1: Configure Virtual Alias Maps

Edit the Postfix main configuration file:

sudo nano /etc/postfix/main.cf

Add or update the virtual alias maps directive:

virtual_alias_maps = hash:/etc/postfix/virtual

Step 2: Create the Catch-All Entry

Open the virtual alias file and add the catch-all rule. The @ symbol followed by your domain name matches any address at that domain:

sudo nano /etc/postfix/virtual

Add the following line:

@yourdomain.com    catchall@yourdomain.com

If you want to forward to a local system user instead:

@yourdomain.com    localuser

Step 3: Build the Hash Map and Reload

Postfix uses hashed lookup tables for performance. Rebuild the map and reload the service:

sudo postmap /etc/postfix/virtual
sudo systemctl reload postfix

Step 4: Test the Configuration

Send a test email to a non-existent address at your domain and verify it arrives in the catch-all mailbox:

echo "Catch-all test" | mail -s "Test catch-all" randomname@yourdomain.com

Check the mail log to confirm delivery:

sudo tail -f /var/log/mail.log

Filtering and Managing Catch-All Mail

Catch-all addresses can attract a large volume of spam. Consider these best practices:

• Use Sieve filters — automatically sort catch-all mail into a separate folder for review
• Enable SpamAssassin — score and tag incoming messages before they reach the catch-all mailbox
• Monitor volume — set up a cron job to alert you if the catch-all volume exceeds a threshold
• Create explicit aliases — once you identify recurring addresses, add them as proper aliases so they bypass the catch-all
• Review periodically — check the catch-all folder weekly to discover addresses that need dedicated mailboxes

Important Considerations

If you are using virtual mailbox domains (with virtual_mailbox_maps), you need to add the catch-all to /etc/postfix/vmailbox instead of the virtual alias file. The entry format differs slightly:

@yourdomain.com    yourdomain.com/catchall/

After editing, rebuild and reload:

sudo postmap /etc/postfix/vmailbox
sudo systemctl reload postfix

A catch-all is a practical safety net, but always pair it with proper spam filtering to keep your mailbox manageable.