Available channels

Every MTA channel has a unique name containing up to 32 characters. Only lowercase letters, numbers, underscores, and dollar signs should be used in channel names.

Certain channel names are reserved for particular uses. Moreover, the MTA  (especially the Job Controller) recognizes  certain families of channel names, (channel name prefixes), and will make internal assumptions about such channels. There are both hard-coded expectations of certain special channel name usage, plus in particular some historical but now wide-spread "conventions" regarding use of  certain   channel names. Using channel names in a conflicting manner can lead to serious problems. MTA administrators are encouraged to use these channels for the stated purposes and in general to pick channel names of their own that do not conflict with these usage conventions.

In addition to the above modern channel names, there are various obsolete or historical channels where use of those old channel names may cause confusion:

See also:
 * TCPIP channels
 * Local channel
 * Bitbucket channel
 * BSMTP channels
 * ims-ms channels
 * Additional ims-ms channels
 * LMTP channels
 * filter_discard channel
 * Generic SMTP channels
 * Pipe channels
 * Process and reprocess channels
 * Conversion channel
 * Defragmentation channel
 * Hold channel
 * Typical TCPIP channels and servers
 * SMTP SUBMIT servers
 * Job Controller
 * Channels