- update pigeonhole to 0.5.6
+ sieve: Redirect loop prevention is sometimes ineffective.
Improve existing loop detection by also recognizing the
X-Sieve-Redirected-From header in incoming messages and
dropping redirect actions when it points to the sending
account. This header is already added by the redirect action,
so this improvement only adds an additional use of this header.
- sieve: Prevent execution of implicit keep upon temporary
failure occurring at runtime.

- update to 2.3.6: (boo#1133624 boo#1133625)
* CVE-2019-11494: Submission-login crashed with signal 11 due to
null pointer access when authentication was aborted by
disconnecting.
* CVE-2019-11499: Submission-login crashed when authentication
was started over TLS secured channel and invalid authentication
message was sent.
* auth: Support password grant with passdb oauth2.
+ Use system default CAs for outbound TLS connections.
+ Simplify array handling with new helper macros.
+ fts_solr: Enable configuring batch_size and soft_commit features.
- lmtp/submission: Fixed various bugs in XCLIENT handling,
including a hang when XCLIENT commands were sent infinitely to
the remote server.
- lmtp/submission: Forwarded multi-line replies were erroneously
sent as two replies to the client.
- lib-smtp: client: Message was not guaranteed to contain CRLF
consistently when CHUNKING was used.
- fts_solr: Plugin was no longer compatible with Solr 7.
- Make it possible to disable certificate checking without
setting ssl_client_ca_* settings.
- pop3c: SSL support was broken.
- mysql: Closing connection twice lead to crash on some systems.
- auth: Multiple oauth2 passdbs crashed auth process on deinit.
- HTTP client connection errors infrequently triggered a
segmentation fault when the connection was idle and not used
for a particular client instance.