CSFE_SVC_ERROR (Adding attachments)
This fix is for a single server install of 8.6 or below… This error can also be caused by the nginx proxy server which is mandatory on an 8.7 server. So this may not apply to a 8.7 server… but…
It seems that the DoSFilter is the root of this. Even-though it does not interfere with normal web client access, uploading attachments triggers it.
Check you zmmailboxd.out file and grep for DoSFilter, look for:
on the IP of the client.
Issue these command to modify the DoSFilter to allow this IP:
zmprov ms <SERVER-NAME> +zimbraHttpThrottleSafeIPs <IP> zmprov mcf +zimbraHttpThrottleSafeIPs <IP>
That should do it.