Link Patterns and Deliverability: URL Shorteners, Tracking Links, and Redirects

Why Links Matter for Deliverability

Spam filters analyze every link in your email. They check the domain reputation of each URL, the number of redirects, whether the visible text matches the actual destination, and whether the link patterns match known spam behaviors.

Links are one of the few content-level signals that still meaningfully affect deliverability. Your sender reputation matters more overall, but bad link practices can tank an otherwise well-authenticated message.

URL Shorteners: Just Don't

Public URL shorteners — bit.ly, tinyurl, goo.gl, ow.ly — are spam filter magnets. The reason is simple: spammers use them constantly to hide phishing and malware URLs.

Shortener	Spam Filter Impact	Recommendation
bit.ly	High risk	Never use in email
tinyurl.com	High risk	Never use in email
t.co (Twitter)	Moderate risk	Avoid in email
Custom branded short domain	Low risk	Fine if reputation is clean

Even if your bit.ly link points to a legitimate page, the shortened URL itself triggers pattern matching in filters that associate it with malicious email.

Practitioner note: A client once shortened every link in their newsletter with bit.ly to "track clicks better." Their inbox placement dropped from 92% to 61% in one send. Removing the shorteners and using their ESP's native click tracking restored placement within two campaigns.

Click Tracking: The Right Way

Most ESPs rewrite your links through their tracking domains for click measurement. This is fine — as long as the tracking domain has good reputation.

Best practices for click tracking:

• Use a custom tracking domain — instead of your ESP's shared tracking domain (like email.mg-sendgrid.com), set up a branded subdomain (like click.yourdomain.com)
• Use HTTPS on your tracking domain
• CNAME your tracking domain to your ESP — this builds reputation on your domain, not theirs
• Keep the redirect chain short — click → tracking domain → final destination (2 hops max)

Setting up a custom tracking domain is one of the easiest deliverability wins available. Your ESP's documentation will have the CNAME instructions.

Redirect Chains

Every redirect adds latency and another domain for filters to evaluate. Keep chains short.

Acceptable:

link in email → tracking.yourdomain.com → final-destination.com

Problematic:

link in email → bit.ly → tracking.yourdomain.com → yourdomain.com/redirect → final-destination.com

Each additional hop gives spam filters another domain to check. If any domain in the chain has poor reputation, the whole link is flagged.

Practitioner note: I've debugged deliverability issues that traced back to a marketing team adding UTM parameters via a separate redirect service — adding a third hop to every link. The redirect domain they used had been abused by other customers. Removing the extra redirect fixed the problem. Use your ESP's built-in UTM parameter support instead.

Link-to-Text Ratio

Too many links in too little text is a spam signal. Spam filters look for patterns like:

• Multiple links in a single paragraph
• More links than sentences
• Links with no surrounding context

Guidelines:

• 1-3 links per 100 words is a safe range
• Always include context around each link — don't just list URLs
• Footer links (privacy, unsubscribe, preferences) are expected and don't count against you

Domain Reputation in Links

Every domain you link to has its own reputation. Linking to a domain that's blacklisted or known for spam/malware will hurt your deliverability.

Check before linking to:

• Affiliate networks (many are associated with spam)
• Partner sites (verify their domain isn't listed)
• User-generated content domains
• File hosting services (some are abused by malware distributors)

Use URIBL/SURBL checks to verify that domains in your email body are clean.

Visible URL vs Actual URL Mismatch

Displaying one URL but linking to another is a phishing indicator:

<!-- BAD: phishing pattern -->
<a href="https://tracking.example.com/click/abc">https://bank.com/login</a>

<!-- GOOD: honest display -->
<a href="https://tracking.example.com/click/abc">Check your account</a>

When the visible text looks like a URL but the href points somewhere different, filters flag it. Use descriptive anchor text instead of displaying URLs that don't match the destination.

Practitioner note: This catches transactional email systems more than marketing. Automated emails that display "https://app.yoursite.com/dashboard" as text but link through a tracking redirect get flagged for URL mismatch. Either skip tracking on those links or use non-URL anchor text.

Testing Your Links

Before sending, verify your link patterns:

1. Run through Mail-Tester — it flags problematic link patterns
2. Check link domains against URIBL/SURBL — ensure no linked domain is listed
3. Verify redirect chains — follow each link and count the hops
4. Test with images off — make sure links are in text, not only in images
5. Verify HTTPS on all URLs including your tracking domain

If your email templates have complex link structures and you're seeing unexplained deliverability issues, schedule a deliverability audit — I'll trace every link in your templates and identify the problematic patterns.

Sources

• Spamhaus: Domain Reputation FAQ
• SpamAssassin: URI-based Rules
• SURBL: How SURBL Works
• Google: Safe Browsing
• M3AAWG: Best Practices for Sending Email

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v1.0 · April 2026