Custom Tracking Domain — Multi-Vendor Rotation, HTTPS, and Per-Region Setup

Beyond the basic setup#

If you've followed Custom tracking domain for click URLs, you have a single click.yourdomain.com CNAME working. This guide is the advanced companion — patterns for production scale.

Pattern A: Multiple tracking domains by campaign type#

click-marketing.brand.com  → marketing emails
click-txn.brand.com        → transactional (password resets, receipts)
click-anno.brand.com       → announcements (product launches, policy updates)

Reasons to separate:

• Reputation isolation — if marketing click-tracker ever gets blocked (rare; can happen via Cloudflare cache poisoning), transactional links keep working
• Per-type analytics — your CDN analytics show traffic per tracking subdomain
• Per-type security policy — transactional can enforce stricter HSTS / CORS than marketing

Setup: register each subdomain as a separate tracking domain in AcelleMail. Attach to different sending servers (matching the campaign type).

Pattern B: HTTPS enforcement#

By default the redirect serves over both HTTP and HTTPS. Force HTTPS-only:

1. AcelleMail admin → Sending → Tracking domains → [your domain] → Settings
2. Enable "Force HTTPS"
3. Ensure your DNS host's TLS cert covers the subdomain (Cloudflare Full/Strict mode or Let's Encrypt on the AcelleMail host)

After enforcement, HTTP requests get 308 → HTTPS. Old links in archived campaigns still resolve (no breakage).

Pattern C: CDN front-end for global latency#

Tracking-redirect adds ~50-200ms per hop depending on recipient's network distance to your AcelleMail server. CDN front-end:

[recipient click] → CDN POP (5-20ms) → AcelleMail origin

Setup (Cloudflare example):

1. Add click.yourdomain.com as a Cloudflare DNS record (proxied = orange cloud)
2. Set Cloudflare SSL mode to Full (Strict) for security
3. Configure Cloudflare Page Rules:
   • Cache Level: Bypass (don't cache redirects; AcelleMail does click counting)
   • Always use HTTPS: On
   • Browser Cache TTL: Respect existing headers

End result: clicks routed through Cloudflare's edge POPs; latency drops 50-150ms for non-US recipients. Cost: $0 (Cloudflare Free tier handles this).

Pattern D: Per-region tracking domains#

For truly global audience with strict latency requirements:

click-us.brand.com    → US-region AcelleMail instance
click-eu.brand.com    → EU-region AcelleMail instance
click-apac.brand.com  → APAC-region AcelleMail instance

Each region's AcelleMail uses its own tracking subdomain. Campaign router picks the right tracking subdomain based on recipient region tag.

For most senders Pattern C (Cloudflare front-end of a single tracking domain) is enough. Pattern D is for $1M+/mo email programs.

Pattern E: Security headers#

The tracking endpoint redirects to external URLs. Modern security headers protect against various attacks:

Add via nginx config (in front of AcelleMail):

add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
add_header X-Content-Type-Options "nosniff" always;
add_header Referrer-Policy "strict-origin-when-cross-origin" always;
add_header X-Frame-Options "DENY" always;

For Cloudflare-fronted setups, configure these via Cloudflare's Page Rules / Workers.

Verify the full setup#

Open the sending-domain detail#

In AcelleMail's sidebar, Sending → Sending domains. The list shows every domain you've registered with status chips (Verified / Pending / Failed) and per-auth indicators:

Click into your domain row. The detail page surfaces exactly which DNS records to publish (TXT for SPF, CNAMEs for DKIM, TXT for DMARC) with copy-paste-ready values + current verification state per check:

Each tracking domain should show Verified in the list. Click into any to see DNS record details + recent traffic stats.

After a campaign send, open the Links report:

Verify the displayed URLs include your custom tracking domain (not acellemail.com default).

The Click log shows per-click events with which tracking domain processed each:

Common UI signals + fixes#

Programmatic verification#

# Daily check: ensure tracking domain is rewriting correctly across recent campaigns
campaign_uids=$(curl -sH "Authorization: Bearer $TOKEN" \
  "https://acellemail.com/api/v1/campaigns?limit=5" | jq -r '.data[].uid')

for uid in $campaign_uids; do
  url=$(curl -sH "Authorization: Bearer $TOKEN" \
    "https://acellemail.com/api/v1/campaigns/$uid/links" \
    | jq -r '.data[0].url')
  if [[ "$url" == *"click.yourdomain.com"* ]]; then
    echo "✓ $uid: tracking domain correctly applied"
  else
    echo "✗ $uid: NOT using custom tracking domain — investigate"
  fi
done

Run as a daily cron. Catches misconfiguration before customer complaints arrive.

// click.yourdomain.com handled by Cloudflare Worker
addEventListener('fetch', event => {
  event.respondWith(handle(event.request))
})

async function handle(req) {
  // Pass through to AcelleMail origin
  const url = new URL(req.url)
  url.hostname = 'acellemail.com'  // your origin
  url.protocol = 'https:'

  // Add custom headers
  const headers = new Headers(req.headers)
  headers.set('X-Forwarded-By', 'cloudflare-tracking')

  // Fetch from origin
  const response = await fetch(url.toString(), {
    method: req.method,
    headers: headers,
    body: req.body,
  })

  // Modify response (e.g. add security headers)
  const newResponse = new Response(response.body, response)
  newResponse.headers.set('Strict-Transport-Security', 'max-age=31536000')
  newResponse.headers.set('X-Frame-Options', 'DENY')

  return newResponse
}

HTTP/1.1 302 Found
Location: https://target.example.com
X-AcelleMail-Campaign: campaign-uid
X-AcelleMail-Subscriber: subscriber-uid
X-AcelleMail-Tracking-Domain: click.brand.com

{
  "event": "subscriber.clicked",
  "campaign_uid": "...",
  "subscriber_uid": "...",
  "tracking_domain": "click.brand.com",
  "destination_url": "https://target.example.com",
  "click_at": "2026-05-20T14:30:00Z",
  "user_agent": "Mozilla/5.0..."
}

Customer A: click.customerA.com
Customer B: click.customerB.com

Marketing campaign 1: click-a.brand.com
Marketing campaign 2: click-b.brand.com
Marketing campaign 3: click-a.brand.com  (rotate)

Related articles#

• Custom tracking domain for click URLs
• Multi-server rotation pattern
• Sending throttling strategies
• Complete DNS setup for email sending