When building notification systems that generate dynamic email addresses (like notification-message-988742@mysite.com), replies sent to these addresses need proper handling. Since these addresses don't have individual mailboxes, we need to redirect them to a central address (notification@mysite.com).

Here are three effective methods to handle wildcard email redirection in Postfix:

1. Using Virtual Aliases

Edit /etc/postfix/virtual:

# Wildcard pattern matching
@notification-message-.*@mysite.com notification@mysite.com

Then run:

postmap /etc/postfix/virtual
postfix reload

2. Regex Table Mapping

Create /etc/postfix/regexp:

/^notification-message-[0-9]+@mysite\.com$/ notification@mysite.com

Add to main.cf:

virtual_alias_maps = regexp:/etc/postfix/regexp

3. Using Transport Maps

For more complex routing, create /etc/postfix/transport:

notification-message-*@mysite.com local:notification

Then:

postmap /etc/postfix/transport
postfix reload

Verify your setup with:

postmap -q "notification-message-123@mysite.com" regexp:/etc/postfix/regexp

You should see the output:

notification@mysite.com

For a complete solution, consider these additional configurations:

# In main.cf
bounce_notice_recipient = notification@mysite.com
notify_classes = bounce, delay, policy, protocol, resource, software

When dealing with high volumes:

• Use hash maps instead of regex for better performance
• Consider implementing a milter for complex filtering
• Monitor your mail queue regularly

Here's a full configuration example:

# /etc/postfix/main.cf additions
virtual_alias_domains = mysite.com
virtual_alias_maps = hash:/etc/postfix/virtual, regexp:/etc/postfix/regexp

With /etc/postfix/virtual containing:

@mysite.com @notification-message
notification@mysite.com notification

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When building notification systems that allow users to reply to messages, we often generate dynamic Reply-To addresses containing unique IDs (like notification-message-988742@mysite.com). These emails don't have individual mailboxes, but need to be routed to a central address (notification@mysite.com) for processing.

Here are two effective approaches to handle wildcard email redirection in Postfix:

Method 1: Using Virtual Aliases

Edit your /etc/postfix/virtual file:

# Wildcard pattern matching
@notification-message-.*@mysite.com notification@mysite.com

Then update the virtual alias database:

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

Method 2: Using Recipient Canonical Maps

Create /etc/postfix/recipient_canonical:

# Map all matching addresses to notification@
notification-message-.+@mysite.com notification@mysite.com

Add to main.cf:

recipient_canonical_maps = regexp:/etc/postfix/recipient_canonical

Reload Postfix:

sudo postmap /etc/postfix/recipient_canonical
sudo systemctl reload postfix

Verify your setup works by sending a test email:

echo "Test" | mail -s "Wildcard Test" notification-message-12345@mysite.com

Then check if it arrives in the notification@mysite.com mailbox.

If emails aren't being redirected properly:

1. Check Postfix logs: tail -f /var/log/mail.log
2. Verify your regex patterns match the email format
3. Ensure you've reloaded Postfix after configuration changes

For a complete solution, you'll need to parse the original message ID from the recipient address. Here's a basic Python example:

import re
from email.utils import parseaddr

def extract_message_id(email):
    header = parseaddr(email)[1]
    match = re.search(r'notification-message-(\d+)@', header)
    return match.group(1) if match else None