Editheader Extension

Relevant specifications
=======================

  RFC5293 - doc/rfc/editheader.rfc5293.txt

Description
===========

The editheader extension [RFC5293] enables sieve scripts to interact with other
components that consume or produce header fields by allowing the script to
delete and add header fields.

Configuration
=============

The editheader is not available by default and needs to be enabled explicitly by
adding it to the sieve_extensions setting.

The following settings can be configured for the editheader extension (default
values are indicated):

sieve_editheader_max_header_size = 2048
  The maximum size in bytes of a header field value passed to the addheader
  command. The minimum value for this setting is 1024 bytes. The value is in
  bytes, unless followed by a k(ilo).

sieve_editheader_protected =
  A space-separated list of headers that cannot be added to nor removed from the
  message header. The `Received:' and `Auto-Submitted:' fields are always
  protected and the `Subject:' header cannot be protected, as required by the
  RFC specification; adding one of these headers to this setting has no effect.

Invalid values for the settings above will make the Sieve interpreter log
a warning and revert to the default values.

Example
=======

plugin {
  # Use editheader
  sieve_extensions = +editheader

  # Header fiels must not exceed one 1k
  sieve_editheader_max_header_size = 1k

  # Protect special header
  sieve_editheader_protected = X-Verified
}