Link Defanger
What Is the Link Defanger?
The link defanger inspects every link in every email before you see it. It resolves shortened URLs, strips tracking parameters, and flags suspicious domains — all automatically. You see the real destination of every link, not what the sender wants you to think.
What It Does
1. Resolves Shortened URLs
Links using URL shorteners (bit.ly, t.co, tinyurl.com, ow.ly, and many others) are automatically resolved to their final destination. Instead of seeing a blind bit.ly/abc123, you see the actual website the link leads to.
In the email, resolved links show the real domain next to the link text with an amber arrow: Click here →example.com
2. Strips Tracking Parameters
Marketing emails are packed with tracking parameters in their URLs. When you click a link with ?utm_source=email&utm_campaign=spring2025&fbclid=abc123, the destination website knows exactly which email you came from, which campaign it was, and potentially your identity.
PrMail automatically strips these tracking parameters from all links:
- Google Analytics:
utm_source,utm_medium,utm_campaign,utm_term,utm_content - Facebook:
fbclid - Google Ads:
gclid,dclid - Microsoft:
msclkid - HubSpot:
_hsenc,_hsmi,__hstc - Marketo:
mkt_tok - Mailchimp:
mc_cid,mc_eid - And many more.
The link still works — it takes you to the same page, but the destination site can no longer track which email brought you there.
3. Flags Suspicious Domains
Links pointing to potentially dangerous domains are highlighted with a red warning. The defanger checks for:
- IP addresses as domains — legitimate sites use domain names, not raw IPs.
- Brand misspellings — domains like
paypa1.com,amaz0n.net,micros0ft.comthat mimic real brands. - Excessive subdomains — like
login.secure.verify.paypal.suspicious-site.com.
Suspicious links are shown with a red warning symbol and the real domain in brackets: ⚠ Click here [suspicious-site.ru]
Privacy Levels
The link defanger runs on Low and Medium privacy levels. On High (plain text mode), all links are shown as visible URLs anyway, so defanging isn't needed.
Important Notes
- Resolved URLs are cached for 24 hours to avoid repeated lookups.
- The defanger processes links when you open the email, not when it arrives.
- Not all shortened URLs can be resolved — some shortening services block automated lookups. In these cases, the original shortened URL is shown.