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Cloudflare & eMarketeer Tracking Parameters

How to configure Cloudflare so email tracking parameters do not cause cache misses

Overview

When eMarketeer sends emails, it automatically appends two tracking parameters to every link:

• utm_em_source — identifies the email as the traffic source
• emtidv2 — a unique tracking ID per recipient and per send

Because these parameters have different values for every recipient and every send, Cloudflare’s default caching behavior treats each click as a request to a unique URL. This means every email click bypasses the cache and hits your origin server directly, negating the performance benefits of Cloudflare.

This article explains how to configure Cloudflare so that these parameters are ignored when determining whether a cached response can be served.

Why This Happens

Cloudflare uses the full URL — including all query parameters — as the cache key by default. So these two URLs are treated as completely different resources:

https://example.com/page?utm_em_source=abc123&emtidv2=xyz789
https://example.com/page?utm_em_source=def456&emtidv2=uvw000

Even though both URLs return identical content, Cloudflare fetches each one from your origin server separately. The fix is to tell Cloudflare to ignore these specific parameters when building the cache key, or to strip them from the URL entirely before caching.

Solutions by Plan

There are two approaches depending on your Cloudflare plan. Both are verified to work on the emarketeer-test.com domain.

Free Plan — URL Rewrite Rule (Transform Rules)

The Free plan does not support custom cache keys for specific query parameters. However, you can use a Transform Rule to rewrite the URL and strip the tracking parameters before Cloudflare evaluates the cache key. This is the most effective free-plan solution, and it also works on Pro, Business, and Enterprise plans.

How it works: Cloudflare processes Transform Rules before caching. By stripping utm_em_source and emtidv2 from the URL at the edge, every email link click arrives at the cache lookup with a clean URL — identical to a direct visit. The parameters are never seen by your origin server either, which keeps your server logs clean.

Step-by-step setup:

1. Log into the Cloudflare dashboard and select your domain.
2. In the left menu, go to Rules → Transform Rules.
3. Click + Create rule and select URL Rewrite Rule.
4. Give it a name, for example: eMarketeer — Strip tracking params
5. Under If incoming requests match, select All incoming requests.
6. Under Then, set Path to Preserve.
7. Under Query, select Rewrite to… and choose Dynamic from the dropdown.
8. Paste the following expression into the expression field:

regex_replace(http.request.uri.query, "(&?(utm_em_source|emtidv2)=[^&]*)", "")

9. Set Place at to First.
10. Click Save. The rule will be enabled automatically.

Note: This rule applies to all incoming requests. The regex safely handles cases where utm_em_source or emtidv2 appear at the start, middle, or end of the query string, and leaves all other parameters intact.

Pro Plan and Above — Cache Rule with Custom Cache Key

On Pro plan and higher, you can configure Cloudflare to exclude specific query parameters from the cache key while preserving all other parameters. This is the cleanest and most precise solution.

Step-by-step setup:

1. Log into the Cloudflare dashboard and select your domain.
2. In the left menu, go to Caching → Cache Rules.
3. Click + Create rule.
4. Give it a name, for example: eMarketeer — Ignore tracking params
5. Set the condition to match your site. To apply to all pages, select All incoming requests. To limit to specific paths, use a URL path condition.
6. Under Cache eligibility, select Eligible for cache.
7. Expand Cache key settings.
8. Under Query string, select Exclude specific parameters and enter:

utm_em_source
emtidv2

9. Click Save and deploy the rule.

This tells Cloudflare: when checking for a cached version of a page, ignore the values of utm_em_source and emtidv2. Requests from different email recipients will all hit the same cache entry.

Also Required: Cache HTML Pages

By default, Cloudflare only caches static files (images, CSS, JS, etc.). HTML pages are not cached unless you explicitly configure it. If your email links point to HTML pages, you also need a Cache Rule to enable caching for those pages.

To cache HTML pages:

1. Go to Caching → Cache Rules.
2. Create a new rule.
3. Set the condition to match your landing pages (or use All incoming requests to cache everything).
4. Under Cache eligibility, select Eligible for cache.
5. Save and deploy.

Important: Be careful enabling “Cache everything” if your site serves personalized or dynamic content. Only enable this for pages that return the same content to all visitors.

Verifying the Configuration

After setting up the rules, verify caching is working by checking the CF-Cache-Status response header.

Using curl:

curl -I "https://yourdomain.com/your-page?utm_em_source=test123&emtidv2=abc456"

Look for the CF-Cache-Status header in the response:

• HIT — served from Cloudflare’s cache ✅
• MISS — fetched from your origin (expected on the first request to a URL)
• BYPASS — caching was bypassed (check for conflicting rules or cookies)
• DYNAMIC — Cloudflare determined the response should not be cached

After the first MISS, make a second request with different values for utm_em_source and emtidv2. If the configuration is correct, you should see HIT because Cloudflare ignores those parameter values when looking up the cache.

Using browser developer tools:

Open DevTools → Network tab, click on the page request, and look for CF-Cache-Status in the Response Headers section.

Summary

The URL Rewrite Rule approach (Free plan) works on all plans and has the added benefit of stripping the tracking parameters before they reach your origin server, keeping your server logs clean.

Troubleshooting

Cache status is always MISS

• Check that the Cache Rule for HTML pages is enabled (Caching → Cache Rules).
• Check for Set-Cookie headers in the response — Cloudflare will not cache responses that set cookies by default.
• Check for Cache-Control: no-store or no-cache headers from your origin.
• Verify that the Transform Rule is Active (not Disabled) under Rules → Transform Rules.

Other query parameters are being stripped

The regex used in the URL Rewrite Rule only targets utm_em_source and emtidv2. All other query parameters are preserved. If you suspect other parameters are being affected, test with a URL that has only those parameters and inspect the request reaching your origin in server logs.

The rule applies to API requests too

If you want to limit the Transform Rule to only apply to specific paths (e.g., your landing pages), change the condition from All incoming requests to a URL path filter. For example: URI path starts with /campaigns/.