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SMTP Adapter

Documentation status: architecture — see Maturity and evidence.

Purpose

The SMTP adapter is an integration boundary for sending email from an application or Runtime service. SMTP is infrastructure; email intent and business policy remain application concerns.

Architecture

application intent
    -> mail service abstraction
    -> SMTP adapter
    -> SMTP server

Design rules

  • keep host, port, credentials, TLS policy, and sender identities outside business code;
  • store secrets in an external secret/configuration mechanism, not in committed service files;
  • separate message creation from transport delivery;
  • define retry policy carefully because submission may have succeeded even when the client did not receive a final acknowledgement;
  • record correlation and delivery diagnostics without logging credentials or sensitive message content.

Status

SMTP capability may be provided through an installed adapter/module. Exact configuration names and loading behavior are version-specific and are not a stable cross-version Runtime contract.