Channel options

Channel options are available to adjust many attributes and aspects of channel operation. Unified Configuration channel options subsume the channel keywords of legacy configuration, as well as the second and optional additional lines of legacy configuration channel definitions; and the Unified Configuration  group allows setting the channel-specific options of legacy configuration (those set in legacy configuration in a channel option file). That is, in legacy configuration, channel keywords would appear after the channel  name on the first line of the channel definition in , and then the second and optional additional lines of a channel definition in   would set the   for a channel and optionally the   and  ; while channel-specific options would be set in the     channel option file.

In Unified Configuration, any desired channel options are set under a named  group; e.g., for options that merely need to be turned on: msconfig&#x3e; set channel:channel-name.option-name or for channel options that take an argument: msconfig&#x3e; set channel:channel-name.option-name option-value Some channel options take arguments; each option argument is limited in general to 40 characters, though some special options allow arguments  of 256 characters (252 characters in iMS 5.2 and earlier), and a few  options  (as of 7.0.5 including    and   )  allow arguments up to 1024 characters.

In Unified Configuration, option argument case is preserved even if not quoted. Quoting is not necessary for most option arguments; but options that take multiple "arguments" (in legacy configuration terms), must in Unified Configuration be set by specifying a single, quoted argument. For instance: msconfig&#x3e; set channel:tcp_local.saslswitchchannel tcp_auth role.channel:tcp_local.saslswitchchannel = tcp_auth msconfig# set channel:tcp_local.backoff "PT30M PT1H PT1H PT2H PT4H PT8H" role.channel:tcp_local.backoff = PT30M PT1H PT1H PT2H PT4H PT8H In legacy configuration, option arguments are normally forced to lowercase, but case will be preserved if the option argument is quoted. Also, while legacy configuration options are normally limited to taking at most five arguments, when the arguments  themselves are quoted that restriction is lifted; (see for instance,  the    channel option).

Note that the channel-specific options -- those set in legacy configuration in channel option files, rather than as legacy configuration channel keywords -- in Unified Configuration are set under the   group,  e.g., msconfig&#x3e; set channel:tcp_local.options.ALLOW_ETRNS_PER_SESSION 2 Since channel-specific options are specific to the type of channel in question -- different types of channels tend to have completely different channel-specific options -- look under the discussions of the specific channel types  to find out details of what channel-specific options are available, as channel-specific options do not appear under the general list of options, nor as channel options.

See also:
 * Alphabetic list of channel options
 * Functional group list of channel options
 * Addresses channel options
 * Attachments and MIME processing channel options
 * BSMTP-specific channel options
 * Character sets and eight bit data channel options
 * Conversion tag and service conversion channel options
 * Display label channel options
 * DKIM channel options
 * Error interpretation channel options
 * File creation in the MTA queue area channel options
 * Gateway or firewall or mailhub channel options
 * Headers channel options
 * Host name channel options
 * Incoming channel match and switch channel options
 * ISC channel options
 * Logging and debugging channel options
 * Long address lists or headers channel options
 * Message hash channel options
 * Message tracking channel options
 * MLS channel options
 * Notification messages and postmaster messages channel options
 * Processing control and job submission channel options
 * Sensitivity limits channel options
 * Sieve filters and delivery flags channel options
 * Size limits on messages channel options
 * Spamfilter channel options
 * SMTP and LMTP protocol channel options
 * TCPIP connections and DNS lookups channel options
 * TLS and SASL channel options
 * Channel configuration
 * Getting option changes to take effect on the MTA
 * Available channels
 * Channels