Why a custom tracking domain matters#
Every link in your AcelleMail campaign is auto-rewritten at send time to route through a tracking redirect. The default redirect lives at acellemail.com/c/abc/... — AcelleMail records the click, then forwards to your real URL.
Two problems with the default:
- Brand inconsistency — recipient sees
acellemail.com in the hover preview before clicking. For B2B audiences, that breaks trust ("why is this routing through a third party?").
- Deliverability signal — Gmail's "show original" pane displays the rewritten URL. Some receivers cross-check sender domain vs link domain; mismatched values can downgrade reputation.
Custom tracking domain = click.yourdomain.com (or any subdomain you pick) handles the redirect instead. Same mechanics, your brand throughout.
The setup in 4 steps#
Step 1: Pick your subdomain#
Convention: click.brand.com or track.brand.com or links.brand.com. Pick a subdomain you don't already use for anything else (it'll be reserved for tracking redirects).
Step 2: Publish the CNAME at your DNS host#
At your DNS provider (Cloudflare, Route 53, Namecheap, etc.), add:
Type: CNAME
Name: click.yourdomain.com (or whatever subdomain you picked)
Value: track.acellemail.com (the AcelleMail tracking endpoint — varies per install)
TTL: 3600 (or default)
Wait for DNS propagation (typically 5-60 minutes; can take up to 24h for stubborn caches).
Step 3: Register the tracking domain in AcelleMail#
In AcelleMail, Sending → Tracking domains → Add tracking domain. Enter click.yourdomain.com + click Verify. AcelleMail dig-checks the CNAME, flips to Verified when propagation is complete.
Step 4: Attach to your sending server#
Open the sending-server detail → Configuration → Tracking domain dropdown → pick the newly verified domain. Save.
From the next campaign send onwards, every link uses your custom tracking domain.
Verify it's working#
After a send, open the campaign report's Links tab:
Hover over any link — the rewritten URL should now show click.yourdomain.com/... not the AcelleMail default. If still showing the default, the sending server config didn't pick up the change (re-save the server config + send a fresh test).
The Click map visualization shows where clicks land — independent of which tracking domain rewrites them:
Common UI signals + fixes#
| Symptom |
Likely cause |
UI fix |
| Tracking domain stays Pending after 1 hour |
CNAME not propagated |
Wait up to 24h; if still pending, verify CNAME at your DNS host points to the correct target |
| Tracking domain Verified but new campaigns still use acellemail.com |
Sending server's tracking-domain field not updated |
Sending server detail → Configuration → Tracking domain → re-pick + save |
| Hover preview shows weird URL (mix of yours + acellemail) |
Cached email body from before the change |
Send a fresh test; old campaigns retain their snapshot of tracking URLs |
| Click reports show clicks but tracking domain says 0 traffic |
DNS resolving differently for some recipients |
Test with dig click.yourdomain.com from multiple regions |
| CNAME conflicts with existing record at subdomain |
Duplicate subdomain reservation |
Pick a different subdomain name; can't have CNAME + A record on same name |
Common conventions#
| Pattern |
Used by |
click.brand.com |
Most common; explicit "this is a click-tracker" signal |
track.brand.com |
Same intent, slightly more technical wording |
links.brand.com |
Friendly; works for marketing-facing audiences |
t.brand.com |
Short for higher-engagement industries (e-commerce flash sales) — saves URL chars in SMS-too |
Stick with one convention across your account — don't have some campaigns route via click. and others via track. (recipients learn to trust the pattern; switching mid-stream creates confusion).
Advanced: HTTPS-only redirects, multi-region tracking, and security headers
HTTPS-only redirects:
By default AcelleMail's tracking domain serves the redirect over both HTTP + HTTPS. To enforce HTTPS-only (recipients clicking via HTTP get auto-upgraded to HTTPS first):
- AcelleMail admin → Sending → Tracking domains → [your domain] → Settings
- Toggle "Force HTTPS"
- Ensure your DNS host's TLS certificate covers the subdomain (Let's Encrypt + Caddy on the AcelleMail host is the common setup)
For Cloudflare-fronted setups, the redirect honors Cloudflare's TLS settings — set Full/Strict mode to prevent downgrade attacks.
Multi-region tracking:
If your audience is global, latency on the redirect matters. A US-hosted AcelleMail receiving Asia-side clicks adds ~200ms per hop. Two patterns:
- CloudFront / Cloudflare CDN in front of your tracking domain — most installs route via Cloudflare for free; the CDN's POP nearest the user handles the redirect
- Multi-region AcelleMail clusters — separate AcelleMail instance per region, each with its own tracking subdomain (
click-us.brand.com, click-eu.brand.com). Per-campaign router selects the right tracking subdomain based on recipient region
For most senders, Cloudflare front-end is sufficient + free.
Security headers on the tracker:
The tracking endpoint redirects external URLs. Best practices:
HTTP Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Frame-Options: DENY
X-Content-Type-Options: nosniff
Referrer-Policy: strict-origin-when-cross-origin
Configure at your nginx / web-server layer. The AcelleMail tracking endpoint doesn't set these by default — you add them via your reverse-proxy config.
Programmatic verification:
# Check tracking domain is rewriting links
campaign_uid="..."
acelle_token="..."
# Fetch a campaign's links report
curl -sH "Authorization: Bearer $acelle_token" \
"https://acellemail.com/api/v1/campaigns/$campaign_uid/links" \
| jq '.data[0].url'
# Should show click.yourdomain.com/..., not acellemail.com/...
Run as a daily cron after sends — catches misconfiguration before customer complaints.
Rotating tracking domains:
For very large operations, multiple tracking domains can isolate reputation per campaign type:
click-marketing.brand.com — marketing emails
click-txn.brand.com — transactional (password resets)
click-ann.brand.com — announcements
Different sending servers route through different tracking domains. If click-marketing ever gets blocked (rare), transactional is unaffected.
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