With the latest update we extend automation capabilities in mail:u with a key feature: connection-related technical information is now recorded at the time an email is received and is available to the entire downstream rule engine.

Until now, such data often remained buried in system logs. You can now access variables like the IP address of the submitting server or the TLS state directly. This unlocks new practical use cases, from precise location-based routing to seamless integrations with external archiving and security solutions.

To make the feature as transparent as possible, we integrated the metadata into the most important administrative interfaces:

1. In the workflow logs

When analyzing email checks you will now see the exact connection parameters at first glance:

• Local: The internal mail:u receiving server and recipient host:port (e.g. 10.XX.XX.XX:2222 (sender-demo.mail-u.cloud)).
• Remote: The sender's IP, port and host (e.g. 46.XX.XX.XX:11111 (demo.extern.de)).
• Source: The role of the submitter (e.g. Sender).
• Additional info: Protocol details such as Used TLS (Yes/No) and SMTPUTF8 (No).

2. In the queue

These data now persist with the message in the queue. In the message detail view under “Metadata” you can read the remote IP (e.g. 45.XX.XX.XX:66666) directly, which greatly speeds up everyday troubleshooting.

The real power of the feature is the combination of condition checks and actions. The following practical example shows how to check whether an email comes from a specific IP address and automatically write that information into an email header.

Step 1: Define the condition

In the Conditions tab you specify when the rule should apply:

1. Type: Select Environment.
2. Check type: Choose Remote IP.
3. Match / Value: Select Equals and enter the desired IP address (for example 127.0.0.1 in a test environment).

Step 2: Define the action

Switch to the Actions tab to configure the modification of the email:

1. Action type: Choose Change header.
2. Operation: Set to Append so existing header lines are not overwritten but extended.
3. Key: Choose Equals and enter the desired header name (for example X-Mlf-Connecting-IP).
4. Replacement Mode: Keep Fixed value.

Step 3: Resolve variables with template preprocessing

Now enter the placeholder for the IP address in the Replace with field:

{{ .Remote.Ip }}

Crucial point: Make sure to check the box for "Template preprocessing". Only with this option will mail:u interpret the entry as a template and replace the placeholder with the actual IP address of the submitting server, instead of treating it as literal text. —

This feature removes tedious manual work for administrators. Since connection information can now be injected directly into the message, downstream systems no longer need to parse log files afterwards. Whether for security appliances, compliance filtering, or custom routing scenarios — mail:u's email processing becomes significantly smarter and more flexible.