diff --git a/apps/api/.env.example b/apps/api/.env.example
index 80c12242..bcc4d158 100644
--- a/apps/api/.env.example
+++ b/apps/api/.env.example
@@ -36,7 +36,7 @@ NODE_ENV=development
 
 # Optional email (invites + password reset + notifications + contact)
 # RESEND_API_KEY=re_...
-# TELEMETRY_EMAIL_FROM=Telemetry Tracker <noreply@tacko.io>
+# TELEMETRY_EMAIL_FROM=Telemetry Tracker <info@telemetry-tracker.com>
 # CONTACT_INBOX_EMAIL=info@telemetry-tracker.com
 # Reply-To for outgoing mail. Hosted cloud defaults to info@telemetry-tracker.com; self-hosted defaults to none.
 # TELEMETRY_EMAIL_REPLY_TO=
diff --git a/apps/api/src/routes/contact.ts b/apps/api/src/routes/contact.ts
index 4d7fe505..b457eb6a 100644
--- a/apps/api/src/routes/contact.ts
+++ b/apps/api/src/routes/contact.ts
@@ -80,7 +80,7 @@ function contactDeliveryError(result: { status?: number; error?: string }): stri
     resendMessage.includes("resend.dev")
   ) {
     return (
-      `Email delivery is blocked by Resend: verify tacko.io (or your sending domain) in the Resend dashboard ` +
+      `Email delivery is blocked by Resend: verify telemetry-tracker.com (or your sending domain) in the Resend dashboard ` +
       `and set TELEMETRY_EMAIL_FROM to an address on that domain (e.g. Telemetry <info@telemetry-tracker.com>). ` +
       `Until then, email ${CONTACT_INBOX} directly.`
     );
diff --git a/docs/BILLING.md b/docs/BILLING.md
index 7ca875bb..77c23ee9 100644
--- a/docs/BILLING.md
+++ b/docs/BILLING.md
@@ -51,10 +51,10 @@ Use this checklist for **telemetry-tracker.com** on Railway (API service only 
 
 #### 2. Verify sending domain
 
-The hosted cloud sends from **tacko.io** (operator domain). `telemetry-tracker.com` is the app URL, not the mail-from domain.
+The hosted cloud sends from **telemetry-tracker.com** (`info@telemetry-tracker.com`), verified in Resend (region `eu-west-1`).
 
-1. **Domains** → **Add domain** → `tacko.io`.
-2. Add the DNS records Resend shows (typically **SPF**, **DKIM**, and optionally **DMARC**) at your DNS host for `tacko.io`.
+1. **Domains** → **Add domain** → `telemetry-tracker.com` (region `eu-west-1`).
+2. Add the DNS records Resend shows (typically **SPF**, **DKIM**, and optionally **DMARC**) at your DNS host for `telemetry-tracker.com`.
 3. Wait until Resend shows the domain as **Verified**.
 
 Recommended sender:
@@ -135,7 +135,7 @@ Test with Stripe CLI or Dashboard **Send test webhook** after deploy.
 
 ## Production checklist
 
-- [ ] Resend domain verified (`tacko.io` or your sending domain) — see [Resend production setup](./BILLING.md#production-setup-hosted-cloud)
+- [ ] Resend domain verified (`telemetry-tracker.com` or your sending domain) — see [Resend production setup](./BILLING.md#production-setup-hosted-cloud)
 - [ ] `RESEND_API_KEY` and `TELEMETRY_EMAIL_FROM` set on Railway API; `/health` shows `"email":"configured"`
 - [ ] Test invite, password reset, and contact form delivery
 - [ ] Stripe webhook URL reachable from the internet