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Emails
Send email from your app, connect a custom sending domain, and brand your auth emails.
The Emails section covers everything your app sends: platform email that works with zero setup, your own sending domain via Resend, branded authentication emails, and transactional email from your app code. It has three tabs: Domain, Auth emails, and App emails.
Platform email (zero setup)
Your app can send email immediately through the platform sender with a daily limit, shown as "N of M emails sent today" with recent sends and their status. Great for getting started; connect your own domain when you want branded senders and higher volume.
Your own sending domain
- Create a resend.com account and save your RESEND_API_KEY in Secrets.
- Enter your domain and click Connect domain. Startbase shows the DNS records to add (type, host, value, priority) with copy buttons.
- Verification polls automatically every few seconds; the status flips to verified once DNS propagates.
Use a subdomain like mail.yourdomain.com for sending. Until your domain verifies, Resend only delivers to your own address from its onboarding sender.
Auth emails and templates
Once a domain is verified, set a sender name and from address and click "Use this domain for auth emails" so sign-up confirmations, magic links, and password resets come from your brand instead of the built-in sender. Five templates are editable: Confirm sign-up, Magic link, Reset password, Invite user, and Change email address. Each has a subject and HTML body.
Keep the template placeholders like {{ .ConfirmationURL }} intact; removing them breaks the email's action link. Clearing a field reverts that template to the default.
Emails your app sends
The App emails tab is the starting point for transactional email in your product: welcome emails on sign-up, weekly digests on a schedule, notifications. Use the suggestion chips or just ask the agent, for example "send a welcome email when someone signs up."