Add SMTP collector

Signed-off-by: Ben Reedy <breed808@breed808.com>

docs/README.md

@@ -28,6 +28,7 @@ This directory contains documentation of the collectors in the windows_exporter,
 - [`process`](collector.process.md)
 - [`remote_fx`](collector.remote_fx.md)
 - [`service`](collector.service.md)
+- [`smtp`](collector.smtp.md)
 - [`system`](collector.system.md)
 - [`tcp`](collector.tcp.md)
 - [`terminal_services`](collector.terminal_services.md)

docs/collector.smtp.md

@@ -0,0 +1,77 @@
+# smtp collector
+
+The smtp collector exposes metrics about the IIS SMTP Server.
+
+**Collector is currently in an experimental state and testing of metrics has not been undertaken.** Feedback on this collector is welcome.
+
+|||
+-|-
+Metric name prefix  | `smtp`
+Data source         | Perflib
+Enabled by default? | No
+
+## Flags
+
+### `--collector.smtp.server-whitelist`
+
+If given, a virtual SMTP server needs to match the whitelist regexp in order for the corresponding metrics to be reported.
+
+### `--collector.smtp.server-blacklist`
+
+If given, a virtual SMTP server needs to *not* match the blacklist regexp in order for the corresponding metrics to be reported.
+
+## Metrics
+
+Name | Description | Type | Labels
+-----|-------------|------|-------
+`windows_smtp_badmailed_messages_bad_pickup_file_total` | Total number of mailformed pickup messages sent to badmail | counter | `server`
+`windows_smtp_badmailed_messages_general_failure_total` | Total number of messages sent to badmail for reasons not associated with a specific counter | counter | `server`
+`windows_smtp_badmailed_messages_hop_count_exceeded_total` | Total number of messages sent to badmail because they had exceeded the maximum hop count | counter | `server`
+`windows_smtp_badmailed_messages_ndr_of_dns_total` | Total number of Delivery Status Notifications sent to badmail because they could not be delivered | counter | `server`
+`windows_smtp_badmailed_messages_no_recipients_total` | Total number of messages sent to badmail because they had no recipients | counter | `server`
+`windows_smtp_badmailed_messages_triggered_via_event_total` | Total number of messages sent to badmail at the request of a server event sink | counter | `server`
+`windows_smtp_bytes_sent_total` | Total number of bytes sent | counter | `server`
+`windows_smtp_bytes_received_total` | Total number of bytes received | counter | `server`
+`windows_smtp_categorizer_queue_length` | Number of messages in the categorizer queue | gauge | `server`
+`windows_smtp_connection_errors_total` | Total number of connection errors | counter | `server`
+`windows_smtp_current_messages_in_local_delivery` | Number of messages that are currently being processed by a server event sink for local delivery | gauge | `server`
+`windows_smtp_directory_drops_total` | Total number of messages placed in a drop directory | counter | `server`
+`windows_smtp_dsn_failures_total` | Total number of failed DSN generation attempts | counter | `server`
+`windows_smtp_dns_queries_total` | Total number of DNS lookups | counter | `server`
+`windows_smtp_etrn_messages_total` | Total number of ETRN messages received by the server | counter | `server`
+`windows_smtp_inbound_connections_current` | Total number of connections currently inbound | gauge | `server`
+`windows_smtp_inbound_connections_total` | Total number of inbound connections received | counter | `server`
+`windows_smtp_local_queue_length` | Number of messages in the local queue | gauge | `server`
+`windows_smtp_local_retry_queue_length` | Number of messages in the local retry queue | gauge | `server`
+`windows_smtp_mail_files_open` | Number of handles to open mail files | gauge | `server`
+`windows_smtp_message_bytes_received_total` | Total number of bytes received in messages | counter | `server`
+`windows_smtp_message_bytes_sent_total` | Total number of bytes sent in messages | counter | `server`
+`windows_smtp_message_delivery_retries_total` | Total number of local deliveries that were retried | counter | `server`
+`windows_smtp_message_send_retries_total` | Total number of outbound message sends that were retried | counter | `server`
+`windows_smtp_messages_currently_undeliverable` | Number of messages that have been reported as currently undeliverable by routing | gauge | `server`
+`windows_smtp_messages_delivered_total` | Total number of messages delivered to local mailboxes | counter | `server`
+`windows_smtp_messages_pending_routing` | Number of messages that have been categorized but not routed | counter | `server`
+`windows_smtp_messages_received_total` | Total number of inbound messages accepted | gauge | `server`
+`windows_smtp_messages_refused_for_address_objects_total` | Total number of messages refused due to no address objects | counter | `server`
+`windows_smtp_messages_refused_for_mail_objects_total` | Total number of messages refused due to no mail objects | counter | `server`
+`windows_smtp_messages_refused_for_size_total` | Total number of messages rejected because they were too big | counter | `server`
+`windows_smtp_messages_sent_total` | Total number of outbound messages sent | counter | `server`
+`windows_smtp_messages_submitted_total` | Total number of messages submitted to queuing for delivery | counter | `server`
+`windows_smtp_ndrs_generated_total` | Total number of non-delivery reports that have been generated | counter | `server`
+`windows_smtp_outbound_connections_current` | Number of connections currently outbound | gauge | `server`
+`windows_smtp_outbound_connections_refused_total` | Total number of connection attempts refused by remote sites | counter | `server`
+`windows_smtp_outbound_connections_total` | Total number of outbound connections attempted | counter | `server`
+`windows_smtp_pickup_directory_messages_retrieved_total` | Total number of messages retrieved from the mail pick-up directory | counter | `server`
+`windows_smtp_queue_files_open` | Number of handles to open queue files | gauge | `server`
+`windows_smtp_remote_queue_length` | Number of messages in the remote queue | gauge | `server`
+`windows_smtp_remote_retry_queue_length` | Number of messages in the retry queue for remote delivery | gauge | `server`
+`windows_smtp_routing_table_lookups_total` | Total number of routing table lookups | counter | `server`
+
+### Example metric
+_This collector does not yet have explained examples, we would appreciate your help adding them!_
+
+## Useful queries
+_This collector does not yet have any useful queries added, we would appreciate your help adding them!_
+
+## Alerting examples
+_This collector does not yet have alerting examples, we would appreciate your help adding them!_