The arguments are explained in the following table.
Specifies the handler name. The string is allowed to contain any character allowed in UNIX file name (that is, anything except slash and NUL). Registration will fail if a handler with the specified name has already been registered.
Specifies the type of a handler, may take the following values:
global handler is called for all messages.
sender-domain handler is called for messages whenever the domain part of the sender address matches the specified domain
recipient-domain handler is called for messages whenever the domain part of one of the recipient addresses matches the specified domain
sender handler is called for messages whenever the sender address matches the specified address
recipient handler is called for messages whenever any of the recipient addresses matches the specified address
Specifies a domain or a mail address for the handler-type.
Not required if the handler type is global.
Specifies the hook priority in the queue of hooks.
Specifies the handler executable file.
Registration will fail if the file does not exist.
Specifies the context. This is an opaque string to be passed to the handler on the command line.
Specifies whether to enable the handler.
Specifies the hooking point. Should be one of: before-queue, before-local, before-remote, before-data.