@msreddy Are you saying that you also get this message when you open roundcube (webmail.domain.you):
Oops… something went wrong!
An internal error has occurred. Your request cannot be processed at this time.
For administrators: Please check the application and/or server error logs for more information.
then you can check this given below solution it’s work for me:
Roundcube:
chown -R hestiamail:www-data /etc/roundcube/
find /etc/roundcube/ -type f -iname "*php" -exec chmod 640 {} \;
chown -R hestiamail:www-data /var/lib/roundcube/
chown -R hestiamail:www-data /var/log/roundcube/
Snappymail:
chown -R hestiamail:www-data /etc/snappymail/
chown -R hestiamail:www-data /var/lib/snappymail/