Each day we see several thousand http error codes in Zimbra's access_log for various types of soap POST requests. E.g.
"POST /service/soap/SyncRequest HTTP/1.1" 500 3474
"POST /Microsoft-Server-ActiveSync?User=example.net%5Cuserid&Cmd=Sync&DeviceId=67766482845485360595252954519&DeviceType=Android HTTP/1.1" 500 1421
"POST /service/soap/SyncGalRequest HTTP/1.1" 500 3386
500 is an http code for "Internal Server Error", so I'm wondering what kind of error Zimbra is experiencing when it logs these entries. Seems to occur for ZCO, Apple, Android, etc. sync clients. Also the Zimbra web client.