No Feedback.  Resolving (at worst, this is a configuration issue).

If they were not saving in an SQL database, most likely it is a 
configuration error.  Plenty of people are using SQL database storage 
just fine (like, for example, me).
Fixed.
Fixed.

Changes have been made in Git for this ticket:

Bug #9942: sent mail folder might be empty

  1 files changed, 4 insertions(+), 3 deletions(-)
http://git.horde.org/horde-git/-/commit/7ab99a0712bdacd82082c30c8b963a8f7e8d15c7

Changes have been made in Git for this ticket:

Bug #9942: Prevent divide by zero errors

  1 files changed, 1 insertions(+), 1 deletions(-)
http://git.horde.org/horde-git/-/commit/e02dab9334308b0344960f4bbe930ecce4f8362d

I can confirm this bug. Preferences with 'SQL Database' were not 
saving. I've changed to files, and now many things began suddenly to 
work.

Two errors arised from this behaviour:

1) No mails in any folder for users. DEBUG error logged:

HORDE: HORDE [imp] PHP ERROR: Division by zero [pid 15454 on line 414 
of "/var/www/horde/web/imp/lib/Mailbox/List.php"]
HORDE: HORDE [imp] PHP ERROR: Division by zero [pid 15454 on line 428 
of "/var/www/horde/web/imp/lib/Mailbox/List.php"]

  I tracked this to imp/lib/Mailbox/List.php:411

         $page_size = $GLOBALS['prefs']->getValue('max_msgs');

There is some problem with reading this preference for user, and the 
application assigned 0. That triggered the division by zero 
afterwards, and the result for the user is that he hasn't any mail 
(panic!).

My first workaround for this was to set explicitly

         $page_size = 30;

2) Users can't reply or compose any message. When composing a new 
message, in the new windows appears only "Loading..." text, with no 
further advance. Debug log shows:

PHP Fatal error:  Call to a member function create() on a non-object 
in /var/www/horde/web/imp/compose
.php on line 902

I think this is related to 'sent-mail' folder creation. But in this 
case, the preference for where to put sent mail couldn't be read, so 
it hanged up forever.

Just changing to files the preference driver solved at least these two 
problems.

when using the sql based sessionhandler the problem came up with 
preferences not saved at all, memcached, file based and php session 
handler are working fine and no problem with preferences at all.

there is also a thread on the mailing list with the same problem from 
another person: session handler and DB issue (Antoine Heskia)

when i change to use the file storage for preferences all work fine, 
preferences are saved

when i change preferences they are not stored in db, but i got the 
confirmation message that they are saved. no exception in apache log 
or in horde log file. database is created from scratch