bootSending email (SMTP)
Need your app to send transactional email — sign-up confirmations, receipts, password resets? bootload runs a managed SMTP relay. Verify a sender domain, mint SMTP credentials, and point your app's mailer at them. No third-party email service to wire up separately.
Create an SMTP account
The sender domain has to be one you've verified (you prove you own it, the same way as a custom domain). Then:
bootload smtp create app-mailer --domain mail.example.com
This prints the host, port, username, and password for the account. Save the password immediately — like every secret on bootload, it's shown only once.
Drop those four values into your application's mailer (most frameworks and libraries take a host, port, username, and password for SMTP with auth), and your app sends through bootload from your verified domain.
Configure your app's SMTP
Point your app's mailer at bootload's managed submission endpoint:
| Setting | Value |
|---|---|
| Host | smtp.bootload.io |
| Port | 1587 |
| Security | STARTTLS |
| Username | the SMTP username from your project's Mail page (or the smtp create output) |
| Password | the matching SMTP password — shown once, store it as a secret |
Why port 1587 and not the usual 587? Every app runs inside its own microVM, and microVMs are blocked from opening direct SMTP connections to the internet (the standard ports 25, 465, and 587) — an anti-abuse measure that keeps the platform off spam blocklists. So instead of the usual 587, bootload exposes a dedicated submission port, 1587, that your app connects to; we relay from there. Everything else is unchanged — your mail is still DKIM-signed and billed at €0.001 per accepted email.
Manage accounts
bootload smtp list # your accounts (passwords are never shown)
bootload smtp remove <name> # revoke an account's credentials
Good to know
- Keep the credentials in a secret, not your image. Store the SMTP password as a project secret and read it from the environment — never bake it into the container.
- Sender reputation rides on a verified domain. Sending from a domain you've verified (with the right DNS records in place) is what keeps your mail out of spam folders; an unverified domain can't be used.
- One account, many senders. A single SMTP account can send as any address at its verified domain — create separate accounts when you want to rotate or revoke credentials independently.