In Fedora 26, the Cyrus IMAP server (
cyrus-imapd) has been upgraded to version 3. This version brings significant new functionality, but it also has some new internal database formats. It has also changed the defaults for some important configuration settings. For these reasons it is important that you read and follow upstream’s upgrade documentation before you initiate an update to Fedora 26.
Important changes to note:
Cyrus version 3 has changed the defaults for two important configuration options:
altnamespace. You may need to add them with their previously default value of
0 if these are not present in your existing configuration.
Cyrus version 3 no longer supports the
berkeley database type. If you have essential databases in that format, it is important that you convert them to a different format before you update your system. However, if you have already updated, don’t panic. The default Fedora configuration does use this format, but only for non-essential databases which you will rebuild while following the update documentation linked above.