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Setting up UTM Rules for the first time? Start with the UTM naming convention playbook to define your approved source, medium, and campaign values before configuring the rules engine.
UTM Rules is a set of rules that runs whenever a link is created or updated. One rule set per workspace. It applies in this order:
  1. Force lowercase (default ON) - Summer_Sale → summer_sale
  2. Space replacement (default _) - summer sale → summer_sale
  3. Max length (default 100) - reject values longer than this
  4. Prohibited values - fail if value contains any banned term
  5. Allowed characters - fail if value contains characters outside the selected set (lowercase, numbers, dots, hyphens)

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When to use it

  • Marketing team of more than one person - drift is guaranteed without rules.
  • Anyone publishing UTMs to a shared analytics tool (GA, Mixpanel) where casing/typos create duplicate rows.
  • Agencies enforcing client-specific naming conventions.

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How to configure

1

Open the rules page

Sidebar → UTM Rules.
2

Set the rules

Configure the rules described below, then toggle Rules Active on. The Rule Preview panel shows how a sample value is transformed.
3

Save and test

Click Save Changes. Try creating a link with bad values. Validation errors appear inline on the failing fields.
UTM Rules page - General Formatting with Space Character Replacement, Force Lowercase toggle, and Max Parameter Length; Validation Rules with Allowed Characters and Prohibited Values; Project Rules, Required Fields, and Conditional Logic tabs; and a live Rule Preview

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What each rule does

  • Space character replacement. Choose how spaces in a value are handled: underscore, hyphen, plus, URL encoded, or removed. With hyphen selected, summer sale becomes summer-sale.
  • Force lowercase. Converts every value to lowercase. Summer_Sale becomes summer_sale. On by default.
  • Max parameter length. Rejects any value longer than the set number of characters.
  • Allowed characters. Rejects values containing characters outside the selected sets: lowercase letters, numbers, underscores, dots.
  • Prohibited values. Flags a value as invalid when it matches a banned term, such as test or draft.

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Real-world example

Force consistency across the whole team:
A marketer types Summer Sale!. It is lowercased and spaced to summer-sale, and a value like test-draft is rejected on save. No more inconsistent campaign names slipping into your analytics.

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Edge cases

Rules cleaning vs validation. Steps 1-2 (lowercase, space replacement) transform values silently. Steps 3-5 (length, prohibited, allowed characters) reject the save with errors.
Default rules ship per workspace. Every new workspace starts with force lowercase on, underscore for spaces, and a 100-character max length automatically. They CAN be turned off using the toggle given in the UTM rules panel but it is ON by default.