Configuration Options Reference

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_fbl_header_insertion enable or disable fbl header insertion
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
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
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
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
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
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
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
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
umem_reap_interval how often to release unused memory
unlink_on_spool_in_failure Whether or not to remove malformed messages
_unsafe_spool allow dangerous spool semantics to be used
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_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 .