Transactional Email Relay

The mail your software sends — receipts, password resets, invoices, alerts — going out over a managed SMTP relay on its own sending domain, separately from the mailboxes your people read. That separation is the point: a marketing blast, or one compromised account, cannot take your password resets down with it. We warm the sending domain, handle bounces and complaints, and give you a dashboard showing what was accepted, deferred, bounced or suppressed.

What you get

  • SMTP credentials for your application, scoped to the relay and revocable without touching anybody's mailbox
  • A sending subdomain with its own SPF and DKIM, aligned for DMARC and warmed up at rising volume
  • Every From address checked against the account that authenticates. Pointing an application at an alias is the classic failure here — we have hit it on our own mail, where Google Workspace answers 535 BadCredentials — so the application authenticates as the real account and sends from an alias that has been added as a verified send-as address. Skip that verification and the From header is rewritten in flight, with no error to tell you.
  • Bounce and complaint handling with a suppression list, so a dead address is not retried forever
  • A delivery dashboard with a per-message log, and a monthly read of what is failing and why

What this does not cover

  • Marketing and newsletter sending. A transactional relay keeps its reputation by carrying only mail somebody is waiting for; put a campaign through it and the receipts pay for it.
  • Mailboxes for people to read and reply in — nothing is delivered here. Business Email Mailbox is the other half.
  • Writing the sending code in your application, though we will tell you what is wrong with it from the logs
  • Authentication on your primary domain. The relay brings its own sending subdomain; if the main domain is still unauthenticated, SPF / DKIM / DMARC Setup covers that.

Who it fits

An application whose mail a user is sitting there waiting for; if the mail you are worried about is written by a person, this is the wrong service and Business Email Mailbox is the right one.

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