Submission configuration

Yarilo runs two submission listeners. MX inbound (port 25) is handled by an external MTA (Postfix, Exim, etc.) which delivers to yarilo via LMTP (port 24).

Service key	Port	Role
`submission`	`587`	Outbound submission — AUTH required, STARTTLS.
`submissions`	`465`	Outbound submission — AUTH required, implicit TLS.

See Services configuration for listener-level settings (port, ssl_mode, haproxy_protocol, auth_allow_cleartext).

`protocol.submission`

Protocol-level behaviour shared across both submission listeners.

`hostname`

Default: the top-level hostname
Type: string
Helm: protocol.submission.hostname

EHLO/HELO banner and Message-ID domain for submission only. Unset means the installation's name; see General. Setting it here does not rename the LMTP banner, the Received: header or a delivered message's Message-ID.

`submission_max_mail_size`

Default: 40M
Type: string
Also accepted as: max_message_size
Helm: protocol.submission.max_message_size

Maximum accepted message size. Takes a size with a unit (40M) or bytes.

`max_line_length`

Default: 4096
Type: integer, bytes
Helm: protocol.submission.max_line_length

Maximum SMTP command or DATA line length.

`submission_max_recipients`

Default: 0
Type: integer
Also accepted as: max_recipients
Helm: protocol.submission.max_recipients

Maximum recipients per message. 0 is unlimited.

`recipient_delimiter`

Default: +
Type: string
Helm: protocol.submission.recipient_delimiter

Subaddress separator: user+tag@domain → user@domain. Empty disables it.

`submission_client_workarounds`

Default: []
Type: list
Values: whitespace-before-path mailbox-for-path
Also accepted as: client_workarounds
Helm: protocol.submission.client_workarounds
See also: lmtp_client_workarounds

Compatibility shims for clients that break the protocol. They do the same as the LMTP workarounds of the same name.

`submission_add_received_header`

Default: true
Type: boolean
Helm: protocol.submission.add_received_header

Prepend a Received: trace header to messages before forwarding. Set it to false to keep the sender's address out of the message.

yaml

protocol:
  submission:
    hostname: mail.example.com
    submission_max_mail_size: 40M
    max_line_length: 4096
    submission_max_recipients: 100
    recipient_delimiter: "+"
    submission_add_received_header: true

Submission (port 587 / 465)

Accepts mail from MUAs. AUTH is required. yarilo-submission-login offers PLAIN and LOGIN, plus whatever yarilo-auth runs: the SCRAM mechanisms its passdbs can verify (-PLUS only over TLS 1.3) and, with OAuth2 configured, OAUTHBEARER and XOAUTH2 (see OAuth 2.0). A refused login answers 535; a mechanism not offered answers 504. After successful authentication and DATA, the message is forwarded to the configured upstream MTA via protocol.submission.relay. If submission_relay_host is empty, submission returns 451.

auth_allow_cleartext: false in the service config blocks AUTH on unencrypted connections; pair it with ssl_mode: starttls (port 587) or ssl_mode: ssl (port 465).

A proxy in front

A proxy or relay that passes the client's address with XCLIENT needs xclient_protocol: true on the listener and its own network in general.xclient.trusted_nets, which is empty by default. Only a peer in that list sees 250-XCLIENT in the EHLO reply and has its forwarded address applied; any other client is not told about XCLIENT. See General settings.

Relay (`protocol.submission.relay`)

Configures the upstream MTA for submission. One TCP connection per message; any transport error returns 451 4.4.0 to the MUA.

`submission_relay_host`

Default: none
Type: string
Also accepted as: host
Helm: protocol.submission.relay.host

Upstream MTA hostname or IP. Empty disables the relay, and submission answers 451.

`submission_relay_port`

Default: 25
Type: integer
Also accepted as: port
Helm: protocol.submission.relay.port

Upstream MTA port.

`submission_relay_user`

Default: none
Type: string
Also accepted as: user
Helm: protocol.submission.relay.user

SASL PLAIN username sent to the upstream; %u (or %{user}) is the session's user. Empty, with no master, sends no AUTH.

`submission_relay_master_user`

Default: none
Type: string
Helm: protocol.submission.relay.master_user

Log in as this master acting for submission_relay_user (the SASL authzid), or for the session's user when that is empty.

`submission_relay_password`

Default: none
Type: string
Also accepted as: password
Helm: protocol.submission.relay.password

SASL PLAIN password, the master's when one is set. Supports ${ENV_VAR}. In the chart, relay.password_secret_ref takes it from a Secret instead.

`submission_relay_ssl`

Default: no
Type: string
Values: no starttls smtps
Also accepted as: ssl
Helm: protocol.submission.relay.ssl

Transport security to the upstream.

`submission_relay_ssl_verify`

Default: true
Type: boolean
Also accepted as: ssl_verify
Helm: protocol.submission.relay.ssl_verify

Verify the upstream's TLS certificate.

`submission_relay_ssl_ca`

Default: none
Type: string
Helm: protocol.submission.relay.ssl_ca

PEM file the upstream certificate is verified against. Empty means the system roots.

`submission_relay_trusted`

Default: false
Type: boolean
Also accepted as: trusted
Helm: protocol.submission.relay.trusted

Send XCLIENT to the upstream with the client's real IP. The upstream must advertise XCLIENT.

`submission_relay_connect_timeout`

Default: 30
Type: integer, seconds
Also accepted as: connect_timeout
Helm: protocol.submission.relay.connect_timeout

TCP connect timeout.

`submission_relay_command_timeout`

Default: 300
Type: integer, seconds
Also accepted as: command_timeout
Helm: protocol.submission.relay.command_timeout

Per-command timeout.

yaml

protocol:
  submission:
    relay:
      submission_relay_host: smtp.example.com
      submission_relay_port: 587
      submission_relay_user: relay-user
      submission_relay_password: "${RELAY_PASSWORD}"
      submission_relay_ssl: starttls
      submission_relay_ssl_verify: true
      submission_relay_trusted: false
      submission_relay_connect_timeout: 30
      submission_relay_command_timeout: 300

Telling the relay who sends

A relay that authenticates through yarilo, such as Postfix with smtpd_sasl_type = dovecot pointed at yarilo-sasl-login, can check the sender against the login (reject_authenticated_sender_login_mismatch). For that it must see the user, not a service account. Log in as a master acting for each user:

yaml

protocol:
  submission:
    relay:
      submission_relay_host: relay.example.internal
      submission_relay_port: 587
      submission_relay_ssl: starttls
      submission_relay_user: "%u"
      submission_relay_master_user: relay-master
      submission_relay_password: "${YARILO_SUBMISSION_RELAY_PASSWORD}"

relay-master must be a master user in yarilo-auth (see Master users).
The session's user is the one it logged in as, by every mechanism: PLAIN, LOGIN, SCRAM, OAUTHBEARER and XOAUTH2.
When the relay needs a user (%u, or a master with no relay user) and the session has none, the message is refused before the relay is dialled.

A relay login that fails, or cannot be made for want of a user, answers the client 451 4.7.0 Temporary authentication failure, try again later. The reason is logged with the session id.

In the Helm chart, relay.password_secret_ref (name, key) gives the password from a Secret to every container that relays, as YARILO_SUBMISSION_RELAY_PASSWORD.

JMAP

JMAP EmailSubmission sends through this same relay, with the same login as the user and the same limits; see JMAP.

Verifying the relay

A relay inside the cluster usually holds a certificate from an internal CA. To verify it against that CA, set submission_relay_ssl_ca to the CA's PEM and keep submission_relay_ssl_verify: true. With internal_tls on, the chart already mounts the internal CA at /etc/yarilo/internal-tls/ca.crt.

WARNING

2.4.3 and earlier delivered a reply a step behind after AUTH through the login, so a client could not send through Submission.

The pre-beta short names — host, port, user, password, ssl, ssl_verify, trusted, connect_timeout, command_timeout — are still accepted.

Submission configuration ​

protocol.submission ​

hostname ​

submission_max_mail_size ​

max_line_length ​

submission_max_recipients ​

recipient_delimiter ​

submission_client_workarounds ​

submission_add_received_header ​

Submission (port 587 / 465) ​

A proxy in front ​

Relay (protocol.submission.relay) ​

submission_relay_host ​

submission_relay_port ​

submission_relay_user ​

submission_relay_master_user ​

submission_relay_password ​

submission_relay_ssl ​

submission_relay_ssl_verify ​

submission_relay_ssl_ca ​

submission_relay_trusted ​

submission_relay_connect_timeout ​

submission_relay_command_timeout ​

Telling the relay who sends ​

JMAP ​

Verifying the relay ​

Submission configuration

`protocol.submission`

`hostname`

`submission_max_mail_size`

`max_line_length`

`submission_max_recipients`

`recipient_delimiter`

`submission_client_workarounds`

`submission_add_received_header`

Submission (port 587 / 465)

A proxy in front

Relay (`protocol.submission.relay`)

`submission_relay_host`

`submission_relay_port`

`submission_relay_user`

`submission_relay_master_user`

`submission_relay_password`

`submission_relay_ssl`

`submission_relay_ssl_verify`

`submission_relay_ssl_ca`

`submission_relay_trusted`

`submission_relay_connect_timeout`

`submission_relay_command_timeout`

Telling the relay who sends

JMAP

Verifying the relay