system failure: error while sending read receipt

[sebastian404]

regards,

me is coming out this error when I have enabled acknowledgment message.

can you help me.

method: [unknown]
msg: system failure: error while sending read receipt
code: service.FAILURE
detail: soap:Receiver
trace: qtp509886383-1288372:https://192.168.1.7:443/service/soap/Se ... d0e6f764e4
request:

Body: {
SendDeliveryReportRequest: {
_jsns: "urn:zimbraMail",
mid: "26243"
}
},
Header: {
context: {
_jsns: "urn:zimbra",
account: {
_content: "diego.serna@grupomas.com.co",
by: "name"
},
authToken: "(removed)",
csrfToken: "0_b1cc1093d90eea361a8c31c003dc40bc6597ed50",
notify: {
seq: 2
},
session: {
_content: 1200688,
id: 1200688
},
userAgent: {
name: "ZimbraWebClient - GC51 (Win)",
version: "8.5.1_GA_3056"
}
}
}