---
title: "Pass Data via URL Parameters in Email Links"
slug: "parameters-in-message-links"
updated: 2026-02-05T16:15:53Z
published: 2026-02-05T16:15:53Z
canonical: "docs.mapp.com/parameters-in-message-links"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Pass Data via URL Parameters in Email Links

### Overview

Mapp Engage lets you personalize URLs within messages using parameters. These link parameters insert static values, personalization placeholders, or system variables into the URL, enabling dynamic content and detailed tracking for each recipient.

### Use Cases

- **Personalized Website Experience:** Use contact data to tailor landing pages linked from an email.
- **Pre-filled Forms:** Auto-fill form fields in downloadable content like whitepapers or brochures.
- **Message Attribution:** Track which message contained a clicked link, enhancing web analytics.

---

### Key Characteristics

- Parameters are added as **name=value** pairs in the query part of a URL (after the `?` symbol).
- Both **static** values and **dynamic placeholders** (e.g. `<%${user['lastname']}%>`) can be used.
- Parameters can be added:
  - **Manually** to individual links in the message
  - **Automatically** to all links via **group settings**
- You can **exclude specific links** from receiving parameters (see: *Exclude Links From Link Parameters*).
- Placeholders must not appear in the **hostname** portion of the URL, as this breaks link tracking.

---

### Link Tracking and Email Format Differences

#### Link Tracking and Redirection

- If link tracking is enabled, Mapp Engage redirects all links through its tracking system before forwarding to the final destination.
- Unsafe characters (e.g. spaces) are automatically URL-encoded (e.g. space = `%20`).
- Redirection is invisible to the recipient and enables tracking of click events.

#### HTML vs. Text Email Parameters

**HTML Emails**

- Use these parameters:
  - `l` – Encoded final destination URL
  - `req` – Personalized request data
- Example of personalized placeholder in the URL:

```xml
http://www.website.com/?FNM=<%${user['lastname']}%>
```

During sendout, resolves to something like:

```xml
http://secure.dmcsystem.com/re?l=6m7...&req=FNM=von%20Sch%F6nburg
```

**Text Emails**

- Use slightly different tracking parameters:
  - `l` – Encoded destination
  - `u` – Full destination URL with parameters
  - `s` – Security signature (e.g. `s=PKPJFBHPPLJGMKHM`)

> [!WARNING]
> Warning
> 
> Do not use parentheses () in message names when used in tracking links. They are not URL-encoded and will break the link.

Content that adapts based on user data, behavior, or conditions, enabling personalized messaging in Mapp Engage.

## Related

- [Exclude Links from Group Link Parameters](/exclude-links-from-link-parameters.md)
- [Add a URL Parameter to a Link in an HTML Email](/add-parameter-to-a-link-manually.md)
- [Add URL Parameters to All Links in an Email](/add-parameters-to-all-links-in-a-message.md)