Wie Klick-Tracking in E-Mail-Signaturen tatsächlich funktioniert
The promise of email signature click tracking sounds simple: embed a link, send an email, and know exactly who clicked. But the reality is a minefield of image blocking, proxy prefetching, and privacy mail filters that can turn your analytics into noise. Most tools slap a tracking pixel on a signature and call it a day, leaving you with inflated open rates and zero click data. Here is how the underlying mechanics actually work, where the data breaks, and what a reliable setup looks like.
The redirect chain that powers every tracked click
Every tracked link in an email signature is a carefully constructed redirect. When you add a link like https://yourdomain.com to a signature, the tracking tool rewrites it to something like https://tracking.service/click/abc123?url=https://yourdomain.com. The recipient’s email client resolves this shortened URL, the tracking server logs the click event, and then issues a 302 or 301 redirect to the final destination.
The critical detail is that this redirect must happen over HTTPS. Modern email clients like Gmail and Outlook Web Access will block or warn on mixed content (HTTP links in an HTTPS email). If your tracking domain uses HTTP, the redirect never fires. The tracking server also needs to preserve the original URL parameters — if the final link includes UTM tags, the redirect must pass them through untouched. A poorly configured redirect chain can strip parameters, breaking campaign attribution.
Image blocking kills pixel-based tracking
Many signature tools still rely on a transparent 1x1 tracking pixel embedded in the signature HTML. The pixel is a small image hosted on the tracking server. When the email client loads the image, the server logs an open event. This works only if images are enabled by default.
Gmail and Apple Mail cache images on their own proxy servers. Gmail’s image proxy fetches the pixel once and serves it from Google’s cache to all recipients, meaning you see one open for every recipient who opens the email. Outlook desktop clients block external images by default. Apple Mail’s Mail Privacy Protection (MPP) prefetches all images in the background, regardless of whether the recipient actually opens the email. This inflates open rates by 30-50% on average.
Click tracking does not suffer from image caching in the same way because clicks require an actual HTTP redirect. But the click event still depends on the email client loading the HTML that contains the link. If the signature is rendered as plain text or stripped of HTML by the recipient’s mail server, the click tracking link never appears.
Proxy prefetching and link scanners
The most deceptive source of false clicks comes from security scanners and proxy prefetchers. When an email arrives in a corporate inbox, the gateway often scans every link by sending a HEAD or GET request to the tracking URL. This registers as a click even though no human touched the link.
Microsoft Defender for Office 365, Proofpoint, and Mimecast all do this. Some scanners follow the redirect chain to the final destination to check for malware. Others only check the tracking domain. The result is that click rates for B2B emails can show 2-3x more clicks than actual engagement.
To mitigate this, advanced tracking tools use a two-step approach: first, serve a lightweight interstitial page that requires JavaScript execution or a user interaction (like a button click) before logging the real click. Second, they filter out requests from known scanner IP ranges. This is not foolproof — some scanners execute JavaScript — but it cuts the noise significantly.
How email clients handle link rewriting
Gmail and Outlook rewrite links in outgoing emails for security. When you send an email through Gmail’s SMTP servers, Gmail may replace your tracking link with its own google.com/url?q= wrapper. This wrapper still redirects to your tracking URL, but it adds an extra hop. The tracking server sees the referrer as google.com instead of the original email context.
Outlook.com does similar rewriting for links in emails sent through its web interface. The key takeaway is that your tracking link must be a valid, resolvable URL that can survive multiple redirects. If your tracking domain has a short TTL or a flaky SSL certificate, the chain breaks and the click is lost.
The safest approach is to use a dedicated tracking subdomain (e.g., track.yourdomain.com) with a long-lived SSL certificate and a low-latency CDN. This avoids the common pitfall of shared tracking domains that get blacklisted by corporate filters.
SPF, DKIM, and DMARC: the invisible gatekeepers
Email authentication protocols directly affect whether your signature’s tracking links even reach the inbox. If your email fails SPF or DKIM checks, the receiving server may quarantine the message or strip the HTML signature entirely. A plain-text email has no click tracking.
SPF (Sender Policy Framework) lists the IP addresses allowed to send email on behalf of your domain. If you send through a third-party service like Resend or SendGrid, you must include their sending IPs in your SPF record. DKIM (DomainKeys Identified Mail) signs the email with a cryptographic key. The tracking domain does not need to match the sending domain for DKIM, but if the signature’s images or links reference a domain that fails DKIM, some clients will block them.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) tells receivers what to do with unauthenticated email. A p=reject policy means emails that fail SPF or DKIM are dropped entirely. Your tracking links never get a chance to load.
The practical fix is to ensure your tracking domain passes DKIM independently. Many tools let you add a CNAME record that delegates the tracking subdomain to their infrastructure. This keeps the tracking domain separate from your sending domain, so a DMARC failure on the sending domain does not kill the tracking links.
How newmail.click handles this
Newmail.click is a free email signature builder that lets you add click tracking and open tracking as a Pro feature. When you enable Pro, every link in your signature is wrapped in a redirect that logs the click, the timestamp, and the user agent. We filter out requests from known proxy prefetchers and link scanners to reduce false positives. You get Slack and email alerts for every click, and we automatically append UTM parameters to tracked links so your campaign attribution stays intact. The free builder includes all the signature templates and customisation you need — the tracking is an optional upgrade for when you need the data.
The only metric that matters is the click you can verify
Image opens are unreliable. Proxy clicks are noise. The only signal that holds weight is a click that came from a real browser, with a real user agent, after the email was delivered. That means you need a tracking setup that survives proxy rewriting, scanner prefetching, and client-side image blocking. If your signature tool cannot distinguish a human click from a bot scan, the data is worse than useless — it is misleading. Build your signature with a tool that respects the technical reality of modern email delivery, and you will get numbers you can actually act on.