Univention Corporate Server 4.3 erratum 627 (extended maintenance)

This update addresses the following issue:
* An issue was discovered in Cyrus IMAP. If sieve script uploading is allowed
  (3.x) or certain non-default sieve options are enabled (2.x), a user with a
  mail account on the service can use a sieve script containing a fileinto
  directive to create any mailbox with administrator privileges, because of
  folder mishandling in autosieve_createfolder() in imap/lmtp_sieve.c.
  (CVE-2019-19783)