Multiple, addrsperfile, single, single sys Channel Options

Addresses per message copy
The MTA allows multiple destination addresses to appear in each queued message copy. Some channel programs, however, may only be able to process messages with one recipient per copy, or with a limited number of recipients, or with a single destination system per message copy. For example, the SMTP client programs for TCP/IP channels only establish a connection to a single remote host in a given transaction, so only addresses to that host can be processed (this despite the fact that a single TCP/IP channel is typically used for all outbound Internet message traffic). Another example is that some SMTP servers may impose a limit on the number of recipients they can handle at one time, and they may not handle errors in this area at all gracefully.

The channel options,  ,  , and   can be used to control how the MTA handles multiple addresses. means that a separate copy of the message should be created for each destination address on the channel. creates a single copy of the message for each destination system (more precisely, each destination domain name) associated with a recipient address. creates a single copy of the message for the entire channel. Note that at least one copy of each message is created for each channel the  message is queued to, regardless of the options used. is the default for all channels marked with the   channel option. Channels marked with one of the  channel options  default to   unless the    option has been set. Prior to 7.0 channels marked with one of the LMTP options defaulted to, as of 7.0 they also default to   unless   has been set. (Actually, calling this the "default" is something of a misnomer - without  SMTP and LMTP channels will be forced to   regardless of the channel setting.  This is done to prevent delivery of messages to the wrong system and possibly to the wrong user.)

These options also affect the Job Controller&#x27;s "sorting" and organization of messages on a channel. The  option causes the Job Controller to organize messages into separate internal lists based on destination domain. (And hence a command such as   will show messages sorted by destination host.)

The  channel option is used to put a limit on the maximum number of recipients that can be associated with a single message file in an MTA channel queue, thus limiting the number of recipients that will be processed in a single operation. This option requires a single integer argument specifying the maximum number of recipient addresses allowed in a message file; if this number is reached the MTA will automatically create additional message files to accomodate them.

Note that the default of  depends on the channel type. For most channel types,  defaults to effectively unlimited (2147483647), but setting an   option on a channel causes   to default to 99, while setting an   option on a channel causes   to default to 999.

The default messages per channel copy setting varies by channel type. The  option is the default for everything except    channels. channels default to  if   is set, and    if it is not. The combination of an explicit  and no    isn&#x27;t allowed on   channels and will be overridden by forcing a  setting of.

See also:
 * smtp Option
 * daemon Option
 * Job Controller
 * qm utility
 * TCPIP channels
 * Processing control and job submission channel options
 * File creation in the MTA queue area channel options
 * Channel options