Log Message:
dovecot2-pigeonhole: updated to 0.5.2

v0.5.2:
+ Implement plugin for the a vendor-defined IMAP capability called
  "FILTER=SIEVE". It adds the ability to manually invoke Sieve filtering
  in IMAP. More information can be found in
  doc/plugins/imap_filter_sieve.txt.
- The Sieve addess test caused an assertion panic for invalid addresses
  with UTF-8 codepoints in the localpart. Fixed by properly detecting
  invalid addresses with UTF-8 codepoints in the localpart and skipping
  these like other invalid addresses while iterating addresses for the
  address test.
- Make the length of the subject header for the vacation response
  configurable and enforce the limit in UTF-8 codepoints rather than
  bytes. The subject header for a vacation response was statically
  truncated to 256 bytes, which is too limited for multi-byte UTF-8
  characters.
- Sieve editheader extension: Fix assertion panic occurring when it is
  used to manipulate a message header with a very large header field.
- Properly abort execution of the sieve_discard script upon error.
  Before, the LDA Sieve plugin attempted to execute the sieve_discard
  script when an error occurs. This can lead to the message being lost.
- Fix the interaction between quota and the sieve_discard script. When
  quota was used together with a sieve_discard script, the message
  delivery did not bounce when the quota was exceeded.