Whether to enable the `submission` service configured in master.cf. This service listens for plain text SMTP connections on port 587 and supports explicit TLS via StartTLS. It is a way for clients to login and submit mails after an inband connection upgrade using StartTLS. ::: {.warning} [RFC 8314](https://www.rfc-editor.org/rfc/rfc8314) discourages the use of explicit TLS for mail submissionn. :::

false