Sending & delivery events
SMTP relay
A service that accepts email from your application or server over SMTP and delivers it for you, so existing software can send through an email platform just by changing its mail settings.
How an SMTP relay works
Instead of delivering mail itself, your app connects to the relay’s SMTP server with a username and password, hands over the message, and the relay takes care of delivery: DKIM signing, retries, bounce handling and reputation.
SMTP relay vs. an email API
- SMTP relay: works with almost any existing software, such as WordPress, legacy apps, printers and framework mailers, with no code changes.
- Email API: faster and more flexible for new code, with structured errors, templates and batch sending.
- Both can deliver through the same platform, with the same tracking and suppression.
SMTP relay in MailCraft
MailCraft gives you SMTP credentials scoped to a verified sending domain. Swap the host, port, username and password in your existing mail settings, and your mail flows through the same pipeline as the API, with the same logs, webhooks and suppression list.
Let MailCraft handle the details
Authentication, bounces, complaints and suppression are built in. Start free with 3,000 emails a month, no credit card required.
Start freeRelated terms
Full glossarySending & delivery events
MTA (Mail Transfer Agent)
The software that routes email between servers over SMTP — the underlying engine that actually delivers a message from sender to recipient.
Email types & metrics
Transactional email
Email triggered by a specific user action and containing information they need as a result — a receipt, password reset, or login alert.
Authentication
DKIM (DomainKeys Identified Mail)
A cryptographic signature added to outgoing email that lets receiving servers verify the message really came from your domain and wasn’t altered in transit.