Log Message:
dovecot2-pigeonhole: update to 0.4.21

v0.4.21:

* redirect action: Always set the X-Sieve-Redirected-From header to
  sieve_user_email if configured. Before, it would use the envelope recipient
  instead if available, which makes no sense if the primary e-mail address is
  available.
+ vacation extension: Allow ignoring the envelope sender while composing the
  "To:" header for the reply. Normally, the "To:" header is \ 
composed from
  the address found in the "Sender", "Resent-From" or \ 
"From" headers that is
  equal to the envelope sender. If none is then found, the bare envelope
  sender is used. This change adds a new setting
  "sieve_vacation_to_header_ignore_envelope". With this setting \ 
enabled, the
  "To:" header is always composed from those headers in the source message.
  The new setting thus allows ignoring the envelope, which is useful e.g.
  when SRS is used.
+ vacation extension: Compose the "To:" header from the full sender address
  found in the first "Sender:", "From:" or \ 
"Resent-From:" header. Before, it
  would create a "To:" header without a phrase part. The new behavior is
  nicer, since the reply will be addressed to the sender by name if possible.
- LDA Sieve plugin: Fixed sequential execution of LDAP-based scripts. A
  missing LDAP-based script could cause the script sequence to exit earlier.
- sieve-filter: Removed the (now) duplicate utf8 to mutf7 mailbox name
  conversion. This caused problems with mailbox names containing UTF-8
  characters. The Dovecot API was changed years ago, but apparently
  sieve-filter was never updated.