500 Internal Server Error in VoiceMail messages web interface
Description
Opening web portal on Imagicle VoiceMail messages page returns this error message

Cause
This issue is caused by the high number of recorded messages (> 200) in the user's personal folder
In the IIS log files (C:\inetpub\logs\LogFiles\W3SVC1) you can see this error:
GET /fw/Apps/SSAM/html/user_newmsg.asp |212|800a0009|Indice_non_incluso_nell'intervallo:_'numerofiles' 80
Solution
Delete old files in the user's personal folder \StonevoiceAS\Apps\SSAM\Users\[User]\recordedmessages
Set Imagicle VoiceMail messages retention, as described here.