IMAP Authentication v0.7 / Nextcloud 16

Hi,
I have problems (re-)activating IMAP Authentication after upgrading to nextcloud 16. So I went to a freshly installed systemd and it doesn’t work either.

System:

  • freshly installed ubuntu 18.04 LTS provisioned by Plesk Onyx (17.8.11).

  • Plesk has a nice (beta) App that installes nextcloud, but my issue happens in both the Plesk app and a manual installation.

  • After installing nexcloud I got some hints in the logfile that there is lack of intl php support and I needed to add php7.2-intl

  • Now I installed "External user authentication " and try to configure it according to the settings of my mailserver ´:

    ‘user_backends’ =>
    array (
    0 =>
    array (
    ‘class’ => ‘OC_User_IMAP’,
    ‘arguments’ =>
    array (
    0 => ‘imap..de’,
    1 => 143,
    2 => ‘tls’,
    3 => ‘.de’,
    4 => true,
    5 => false,
    ),
    ),
    ),

An IMAP User can’t log in, log says:
“ERROR: Could not connect via roundcube lib: The Auth_SASL package is required for DIGEST-MD5 authentication”

But Auth_SASL is installed:

# /usr/share/psa-pear/pear/pear list
Installed packages, channel pear.php.net:
=========================================
Package   Version State
Auth_SASL 1.1.0   stable

Same Error message for port 993/ssl

???
Any Ideas?

Thanks,
Boas