emailsender

E-mail sending yuno. It speaks native SMTPS (implicit TLS, RFC 8314) and queues outgoing messages with TimeRanger2 persistence so they survive transient SMTP outages and yuno restarts. Builds fully static since 7.4.3.

Architecture¶

C_EMAILSENDER          <- queueing, retry, dead-letter, MIME encoding
    > C_SMTP_SESSION   <- SMTP client FSM (banner/EHLO/AUTH/MAIL/RCPT/DATA)
        > C_TCP        <- smtps://host:465 (implicit TLS from byte zero)

• C_EMAILSENDER owns two persistent queues on TimeRanger2: emails_queue (pending) and emails_failed (dead-letter). It builds the full RFC 5322 / MIME message (mime_encoder.c) and drives the send/retry loop.

• C_SMTP_SESSION implements the line-based SMTP client as an FSM. It uses AUTH PLAIN; STARTTLS is not implemented (the transport is TLS from the first byte via the smtps:// C_TCP bottom). EHLO advertises the local hostname. An idle session closed by the server (SMTP 421 — OVH does this aggressively) is treated as a graceful close; C_TCP reconnects on the next send.

Configuration¶

Effective config is the usual merge of main.c fixed/variable config with the external JSON; inspect it at runtime with ycommand command-yuno id=<id> service=__yuno__ command=view-config.

url, from, username and password are persistent attributes: set them at runtime with the set-email-user / set-url-from commands (below) and they are saved to the yuno’s persistent-attrs store and reloaded on restart. This is the canonical way to provision the SMTP credentials — they never have to appear in any committed config or batch file. | timeout_dequeue | 10 | ms between queue polls | | max_retries | 4 | Max total send attempts before dead-lettering | | disable_alarm_emails | false | Drop “ALERT Queuing” alarm emails | | tranger_path / tranger_database | | TimeRanger2 store location | | topic_emails_queue | emails_queue | Pending-queue topic | | topic_emails_failed | emails_failed | Dead-letter topic | | backup_queue_size | 1000000 | Backup the queue topic at this size |

C_SMTP_SESSION adds timeout_response (default 30000 ms) — the per-command watchdog while waiting for a server reply.

Commands¶

set-email-user and set-url-from are tagged SDF_AUTHZ_X — they require the __execute_command__ permission when the per-command authz gate is enabled.

Other yunos send mail by publishing EV_SEND_EMAIL to the emailsender service (e.g. logcenter’s summary report).

Delivery semantics¶

Outgoing messages are held in the persistent emails_queue and are never dropped while waiting:

• A message is only dispatched while the SMTP session is connected and authenticated. If the server is down, the URL is wrong, or credentials are rejected, the message stays in the queue. C_TCP keeps reconnecting on its own and delivery resumes once the link is back — nothing is dead-lettered just because the link is momentarily unavailable.

• The body is persisted as part of the queued message (a string), so it survives both retries and a yuno restart.

• A message stays at the head of the queue until it is either sent or its attempts are exhausted. A transient send failure (server NACK, connection dropped mid-send) is retried up to max_retries total attempts.

• When max_retries is exhausted — or the message is permanently undeliverable (missing recipient, un-encodable body) — it is moved to emails_failed and removed from the main queue. The dead-letter queue is not retried automatically.

Every outcome is logged: a warning per retry, an error when a message is moved to the dead-letter queue, and an info line on success.

Debugging¶

Trace levels (enable with ycommand command-yuno id=<id> service=__yuno__ command=set-gclass-trace gclass=<G> set=1 level=<L>):