Sending & 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.
Where the MTA fits
Sending an email involves several pieces. Your app or mail client hands the message to an MTA, the MTA looks up the recipient domain’s MX records, and it connects over SMTP to deliver the message to the receiving MTA, which stores it in the recipient’s mailbox.
Postfix, Exim and commercial engines like PowerMTA are common MTAs.
What an MTA handles for you
- Queueing mail and retrying temporary failures.
- Respecting each provider’s rate limits and connection rules.
- Signing messages with DKIM.
- Processing bounces and reporting delivery results.
Running your own vs. using a platform
Running an MTA yourself means managing IP reputation, feedback loops, bounce handling and provider-specific throttling. An email platform like MailCraft runs that layer for you, and you reach it through an API or an SMTP relay.
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.
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Full glossarySending & delivery events
MX record
A DNS record that specifies which mail servers are responsible for receiving email on behalf of a domain, and in what priority order.
Sending & delivery events
Soft bounce
A temporary delivery failure — a full mailbox or a momentarily unreachable server. Soft bounces are worth retrying a few times before giving up.
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.