Custom tracking domains for cold email. Are they worth the deliverability risk

track_debate · 2026-03-22 · 1,620 views

The tracking domain question comes up constantly. Should you set up a custom tracking domain (like track.yourdomain.com) for your cold email link tracking? Should you use the default tracking domain from your sending platform? Or should you skip tracking entirely? I tested all three approaches across 6 months of campaigns. Here is what I found.

Option 1: Default platform tracking domain. When you enable link or open tracking in Instantly, Smartlead, or any sending platform, they replace your links with a redirect through their tracking domain. Something like track.instantly.ai/redirect/abc123. The problem: that tracking domain is shared across every user on the platform. If other senders on that domain are spammy (and some always are), the shared tracking domain accumulates negative reputation. Your emails inherit that reputation. In my testing, emails with default platform tracking links had 12% worse inbox placement compared to emails with no tracking at all.

Option 2: Custom tracking domain. You set up a subdomain like track.yourcompany.com and configure it as a CNAME pointing to your sending platform's tracking infrastructure. Now your tracking links go through your own domain, which isolates you from other senders' reputation. Inbox placement improved by about 8% compared to default platform tracking. But it was still 4-5% worse than no tracking at all. The reason: email providers can still detect the redirect pattern. A link that goes to track.yourcompany.com/redirect/abc123 and then bounces to your real URL still looks like tracked email, not a personal message.

Option 3: No tracking at all. Disable open tracking. Disable link tracking. No tracking pixels. No redirect links. Just plain text email with direct URLs (or no URLs in email 1, which is best practice anyway). This produced the best inbox placement across every test. Emails looked like a real human wrote them because there was no tracking code injected into the message.

My recommendation: Skip tracking entirely for cold email. Do not track opens. The data is unreliable anyway. Privacy tools, image blocking, and Apple Mail Privacy Protection inflate open rates to meaningless numbers. Do not track link clicks in the first email. Save links for follow-ups, and even then consider whether click data is worth the deliverability hit.

If you absolutely must track links (maybe your team requires click data for reporting), use a custom tracking domain. It is better than shared platform tracking. But understand that you are trading some deliverability for data. For most cold email operations, reply rate is the only metric that matters, and you do not need any tracking code to measure replies.

The safest setup for cold email: plain text, no links in email 1, no tracking pixels, no link tracking. Send from pre-warmed Google Workspace or Outlook inboxes with clean DNS. Measure success by replies and meetings booked. Everything else is noise.