Symptoms
Logging to Horde, there is the following message in one of the frames:Warning: fopen(C:\WINDOWS\Temp\horde.log) [function.fopen]: failed to open stream: Permission denied in C:\inetpub\vhosts\webmail\horde\pear\Log\file.php on line 202
Or
Warning: fopen(C:\WINDOWS\Temp\horde81.log) [function.fopen]: failed to open stream: Permission denied in C:\inetpub\vhosts\webmail\horde\pear\Log\file.php on line 202;
Cause
The user, under which the Horde Application is running doesn’t have sufficient permissions for the log file: C:\WINDOWS\Temp\horde.log, or C:\WINDOWS\Temp\horde81.log
Resolution
Add Modify permissions for the file C:\WINDOWS\Temp\horde.log, or C:\WINDOWS\Temp\horde81.log for the user IUSRPlesk_horde.