| Name | Description |
|---|---|
| adaptive_backstore_leveldb | use LevelDB as the backing store for Adaptive Delivery |
| adaptive_backstore_riak | set characteristics of the Riak backing store |
| adaptive_enabled | enable or disable the adaptive module |
| adaptive_scope | define the scope applicable to adaptive delivery (AD) |
| address_metrics_cleanse_interval | the interval for refreshing address metrics |
| address_metrics_lifetime | the TTL of address metrics |
| alias_schemes | enable named alias expansion schemes |
| allow_ip_literal | allow IP addresses in email addresses |
| allow_null_envelope_sender | allow the null envelope sender in e-mail addresses |
| allow_trailing_whitespace_in_commands | permit trailing whitespace at the end of an SMTP command |
| async_bounce_rendering | which thread pool to use for bounce rendering |
| authorization | configure the console commands applicable to users |
| bind_address | source address for outbound connections |
| binding | configure binding specific options |
| binding_auto_replumb | enable or disable the auto replumber |
| binding_auto_replumb_interval | sets the time interval to check the plumbed state of statically plumbed bindings |
| binding_group | logically group a set of bindings |
| blackhole | blackhole mail |
| body_timeout | network timeout once the DATA phase is complete |
| bounce_behavior | configure the action taken when a message is classified as a bounce |
| bounce_domains | configure the list of domains eligible for bounce processing by Momentum. |
| bounce_pattern | configure the pattern that inbound email addresses must match in order to be considered bounces. |
| bounce_suppress_list | configure a list of email addresses that may not be considered original recipients. |
| bounces_inline_original | how much of the original message to include in MDNs |
| capabilities | selectively retain "root" capabilities |
| chroot | chroot to a secure environment |
| clear_mail_queue_maintainers | reschedule the mail queue maintainer |
| click_tracking_enabled | enable or disable click tracking for SMTP injections |
| click_tracking_scheme | set the hyperlink scheme to use for click tracking links in SMTP injections |
| cluster_max_outbound_connections | set the maximum number of outbound connections for a scope and enforce it across a cluster |
| cluster_outbound_throttle_connections | limit the rate at which connections are established, and enforce it across a cluster of systems |
| cluster_outbound_throttle_messages | limit the rate at which messages are delivered, and enforce it across the cluster |
| cluster_scope_max_outbound_connections | provide traffic shaping for outbound connections in a cluster configuration |
| cluster_server_max_outbound_connections | set the maximum number of outbound connections, and enforce it across a cluster |
| connect_timeout | set the connection timeout |
| connect_timeout_to_delay | time interval before sweeping mail into the delayed queue |
| connection_allocation_aggressiveness | tune the aggressiveness for establishing new connections to domains |
| context | use to set arbitrary connection context key value pairs. |
| control_client_timeout | network timeout for Momentum control client connections |
| crypto_engine | enable hardware cryptography acceleration |
| crypto_lock_method | set the locking method used by the TLS layer |
| debug_flags | configure debug verbosity |
| default_binding | control usage of the "default" binding |
| default_charset | control usage of the "default" character set |
| delay_dsn_max_retry_interval | maximum interval for sending DSNs to the sender of a message that has not yet been delivered |
| delay_dsn_retry_interval | base interval for sending DSNs to the sender of a message that has not yet been delivered |
| delayed_binding_domain_fuzz | length of time to spread scheduled messages over when a bulk requeue is necessary |
| delayed_queue_scan_interval | how often to call the maintainer for a domain |
| delivery_method | set the delivery method |
| delivery_pool | associate a pool of event loops with email delivery to use multiple threads |
| delivery_response_timeout | time to wait for a response to an outbound request |
| disable_nagle_algorithm | disable nagle algorithm on sockets |
| disk_queue_drain_rate | control the rate at which messages are spooled in on start-up |
| dns_cache_purge_interval | how often the DNS response cache is scanned for stale entries |
| dns_expire_interval | how often to check for domains with expired DNS information |
| dns_failures_to_purge | configure the maximum number of DNS lookups |
| dns_fallback_to_tcp | whether or not to fail over to TCP in place of UDP |
| domain_for_unqualified_recipient_addresses | configure a domain which will be used to resolve delivery for unqualified addresses |
| domain_for_unqualified_sender_address | configure a domain which will be used to substitute for unqualified sender addresses |
| domain | configure domain specific options |
| domainkeys | enable or disable domainkeys signing |
| drop_body_after_trans_fail | number of retry attempts before freeing message memory |
| ecstream_port | configure the port for ecstream deliveries |
| ecstream_timeout | the amount of time to wait for an ecstream connection to be established |
| ehlo_hostname | set the hostname used for EHLO in outbound mail |
| ehlo_timeout | network timeout for EHLO |
| enable_dane | enable application of DANE TLS verification on email delivery to a remote domain |
| enable_fbl_header_insertion | enable or disable fbl header insertion |
| enable_mta_sts | enable application of MTA-STS policy on email delivery to a remote domain |
| event_loop | associate a pool of event loops within a listener scope to use multiple threads |
| eventloop | define a pool of event loops to enable multiple event loop configuration |
| events_per_iter | employ when using a concurrency greater than 1. |
| exclude_vctx_conn | exclude validation context keys from being journaled in the spool metadata. |
| exclude_vctx_mess | exclude validation context keys from being journaled in the spool metadata. |
| expensive_batch_assessment | only treat messages as different if the headers are rendered differently |
| force_fsync | ensure that data is synced to disk on reception |
| fully_resolve_before_smtp | resolve all MX and A records before attempting delivery |
| gateway | configure a static SMTP route for mail |
| generate_bounces | generate MDNs if mail is failed after reception |
| generate_bounces_for_multi_recipient_policy_rejections | generate MDNs after reception for policy rejections |
| generate_delay_dsn | generate DSNs if mail is delayed |
| growbuf_size | The size of an element in a growbuf chain |
| host | configure host specific options |
| hostname | override the system configured hostname |
| host_failure_retry | time to wait before attempting a retry |
| hot_domains | list of high-traffic domains that should be spread across maintainer threads |
| http_basic_auth | Define the user credentials when using basic HTTP authentication |
| http_host | Define the HTTP host |
| http_method | Define the HTTP method to use |
| http_uri | Define the HTTP URI that you wish to connect to |
| http_version | Define the HTTP version to use |
| idle_timeout | time to maintain idle outbound connections |
| inbound_throttle_messages | rate limit inbound mail |
| initial_hash_buckets | Set the number of hash buckets used by the system |
| inline_transfail_processing | how to handle transient failure processing |
| keep_message_dicts_in_memory | preserve memory representation of metadata when memory is low |
| large_message_threshold | Consider a message large when its size exceeds this amount |
| legacy_message_threshold | The maximum size allowed for messages being passed to legacy modules |
| license | specify an alternate license location |
| lmtp_port | configure the port for LMTP deliveries |
| local_changes_file | the file for writing local configuration changes |
| local_changes_only | whether there is a file for writing local configuration changes |
| mail_queue_check_vm_interval | how often to apply memory management reduction on mail queues |
| mailerdaemon | set the From: address for MDNs |
| mailfrom_timeout | timeout after MAIL FROM |
| maintainer_pool | associate a pool of event loops with mail queues, DNS lookup, and module events to use multiple threads |
| malloc2mmap_threshold | use mmap when allocations exceed this amount |
| masterdb_file | specify an alternate path for the statistics permastore |
| match_cache_life | set the maximum number of seconds that the match cache will be valid |
| match_cache_size | the size of the cache that holds the results of looking up matching scopes |
| max_deliveries_per_connection | maximum number of messages to deliver before closing a connection |
| max_dns_ttl | set the maximum DNS TTL |
| max_outbound_connections | set the maximum number of outbound connections for a domain |
| max_recipients_per_batch | maximum number of recipients to send in a single outbound message transaction |
| max_request_size | maximum size of an HTTP request |
| max_resident_active_queue | threshold above which messages are not held in memory |
| max_resident_messages | threshold above which messages are not held in memory |
| max_resident_transfails | the threshold for swapping transient failures out of memory |
| swap_out_meta_after_each_tempfail | controls whether or not Momentum will update metadata such as num_retries, next_attempt, and message context on disk after each tempfail. |
| max_retries | override the system configured max_retries |
| max_retry_interval | maximum retry interval |
| max_timed_events_per_iter | the maximum numer of timed events per scheduler iteration |
| mdn_failures_notify | mailbox to which to send null recipient MDNs |
| memory_goal | configure physical memory usage goal |
| memory_hwm | configure physical memory usage high-water mark |
| message_expiration | the time to live for messages |
| migrate_connections_between_sibling_domains | optimize connections for sibling domains |
| mime_parse_large_messages_during_reception | configure whether large messages are parsed upon reception or just in time. |
| min_dns_ttl | override DNS TTLs smaller than this value |
| mta_sts_dns_cname_max_depth | the maximum number of continuous CNAME lookups while doing MTA-STS DNS TXT lookup |
| mta_sts_policy_store | the directory to store MTA-STS policy files |
| mx_failures_fallback_to_a | configure the maximum number of times an MX lookup will be attempted |
| mx_failures_to_delay | number of consecutive failures before a domain is auto-delayed |
| never_attempt_expired_messages | Never attempt delivery of expired messages |
| never_retry | whether or not to retry delivery of failed messages |
| only_use_best_mx_for_relay_domains | If this is set to true, only the lowest numerical priority MXs are used when sending to domains listed in bounce_domains or relay_domains. |
| open_relay | whether the MTA is an open relay or not |
| open_tracking_enabled | enable or disable open tracking for SMTP injections |
| open_tracking_scheme | set the hyperlink scheme to use for open tracking links in SMTP injections |
| opendkim_sign | whether or not to enable OpenDKIM signing |
| outbound_throttle_connections | limit the rate at which connections are established |
| outbound_throttle_messages | limit the rate at which messages are delivered |
| pathway | a grouping of inbound configuration options |
| pathway_group | a container for pathways |
| pcre_cache_size | set the maximum size of the ec_pcre_compile cache |
| pcre_cache_ttl | set the maximum TTL for the ec_pcre_compile cache |
| permastore_interval | the frequency for saving various statistics |
| pidfile | set the PID file path |
| prefer_ipv6_mxs | prefer IPv6 addresses over ipv4 at a given mx priority level |
| prohibited_hosts | prevent mail from being delivered to invalid destinations |
| rcptto_timeout | timeout after RCPT TO |
| relay_for_sending_domains | domains that may use the MTA as a relay. |
| relay_domains | configure the list of domains for which Momentum relays mail |
| relay_hosts | configure the list of hosts for which Momentum relays mail |
| remote_smtp_port | set the port to be used for SMTP deliveries |
| require_ehlo | reject mail from clients that don't say HELO |
| reserve_maintenance_interval | how often to perform mail queue maintenance |
| resolv_conf | specify a custom resolv.conf |
| response_transcode_pattern | the regex pattern for comparison to a server response |
| response_transcode_replace | the replacement string for a server response |
| retry_interval | base retry interval |
| rfc2821_allow_whitespace_in_envelope | permit trailing whitespace before the final CRLF |
| rfc2821_pedantic_address_rules | Allow relaxation of enforcement of the rfc2821 address rules. |
| rfc2822_date_header | rfc2822 conformance |
| rfc2822_lone_lf_in_body | rfc2822 conformance |
| rfc2822_lone_lf_in_headers | rfc2822 conformance |
| rfc2822_max_line_length | rfc2822 conformance |
| rfc2822_max_line_length_policy | determine how non-RFC-compliant line lengths are handled |
| rfc2822_messageid_header | rfc2822 conformance |
| rfc2822_missing_headers | rfc2822 conformance |
| rfc2822_trace_headers | rfc2822 conformance |
| rollup_mx | MX Rollup enable/disable |
| rollup_mx_name | MX Rollup routing domain specification |
| routes | configure message routing |
| rset_timeout | set the timeout after RSET |
| scope_max_outbound_connections | provide traffic shaping for outbound connections |
| scheduler | override the default IO scheduler |
| security | Scope for defining which permissions are retained by which user |
| send_8bitmime | Enable advertising of 8BITMIME when sending mail |
| server_max_file_descriptors | sets the maximum number of file descriptors usable by the system |
| server_max_outbound_connections | sets the maximum number of outbound connections |
| server_reserve_outbound_connections | sets the server-wide connection limit reserve |
| signing_stats | control how signing statistics are recorded |
| siv_throttle_cache_size | set the maximum number of named throttles |
| skip_hosts | skip the specified host, but consider other hosts in the domain |
| SNMP | Simple Network Management Protocol Support |
| soft_bounce_drain_rate | how many soft bounces to place into the mail queues in a single scheduler iteration |
| spool_mode | set the file mode for newly created spool files |
| spoolbase | set the base directory for the spool |
| ssl_lock_method | the SSL lock method |
| starttls_injection_policy | protect against SMTP injections prior to TLS |
| supplemental_groups | security: supplemental groups to assume after startup |
| suspend_delivery | prevent outbound mail delivery |
| tcp_buffer_size | maximum tcp buffer size for outbound connections |
| threadpool | configure thread pool specific options |
| timestampformat | set the timestamp format used when logging to stderr |
| tls | determine whether to use TLS connection for outbound mail |
| tls_allow_renegotiation | determine whether to enable TLS renegotiation |
| tls_ca | certificate authority for outbound mail |
| tls_certificate | certificate to use for inbound and outbound mail |
| tls_ciphers | specify allowable ciphers for TLS inbound and outbound sessions |
| tlsv13_ciphersuites | specify allowable TLSv1.3 ciphersuites for TLS inbound and outbound sessions |
| tls_client_ca | certificate authority for inbound mail |
| tls_dhparams_file | specifies the file of Diffie Hellman (DHE) parameters that add per-session randomness to the encryption. Default parameters are built in the product if none are specified. |
| tls_enable_dhe_ciphers | controls whether or not Diffie Hellman (DHE) ciphers are available |
| tls_engine | specify the TLS library to use |
| tls_ifavailable_fallback | determine the behavior if TLS negotiation fails |
| tls_key | TLS key to use for outbound or inbound mail |
| tls_protocols | allowable ciphers for TLS inbound and outbound sessions |
| tls_verified_peer_is_authorized | Marks requests that use a verified SSL Client certificate as being authorized |
| tls_verify | specify how to handle the remote presented certificate |
| tls_verify_mode | determine whether a TLS certificate is required |
| tlsa_expire_interval | how often to check for expired TLSA records |
| trace_smtp_mode | set the default permissions of trace files |
| tracking_domain | set the tracking domain to use for engagement tracking in SMTP injections |
| tracking_link_expiry | set the expiration time for engagement tracking for SMTP injections |
| transfail_drain_rate | the maximum number of messages to pop off the transient failure queue in a single scheduler iteration |
| transform_8bitmime_content | Enable 8BITMIME downconversion when sending mail |
| unlink_on_spool_in_failure | Whether or not to remove malformed messages |
| _unsafe_spool | allow dangerous spool semantics to be used |
| use_dane | enable DNSSEC validation on MX/A records, if both secure, TLSA record is fetched and DNSSEC validation is done for a domain |
| use_iflist_cache | Whether or not to cache the list of network interfaces configured by the system |
| use_ipv6 | Affects the selection of IPv6 hosts in the SMTP client |
| use_mmap | use mmap when spooling messages from disk |
| use_mta_sts | fetch MTA-STS policy for a domain |
| use_sendfile | use sendfile() when sending mail |
| user | security: user identity to assume after startup |
| xclient | use the xclient extension to SMTP for outbound mail |
This chapter provides the definitions of the configuration options for the configuration files that are referenced in this document.
Most options that are common to Momentum 4 and Momentum 3 are documented in the Momentum 3.x Reference Manual. See the Configuration Options Summary .
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