When you run the query, the value will be expanded in the property singleValueExtendedProperties as below.
If you are using the SDK assuming you are using .Net SDK for example, you can do
var messages = await graphServiceClient
.Users["user-id"]
.Messages
.Request()
.Select("id,subject")
.Expand("SingleValueExtendedProperties($filter=(Id eq 'Binary 0x0E0A'))")
.GetAsync();
This will return data that looks like:
[
{
"subject": "Subject goes here.",
"singleValueExtendedProperties": [
{
"value": "AAAAAMEqF24GH9hBjk0AEaj0EDABABWeiu9p+xxMo+DU7D1wckAAAAAAAQkAAA==",
"id": "Binary 0xe0a",
"@odata.type": null
}
],
"id": "AAMkAG...Vr9AAA=",
"@odata.type": "microsoft.graph.message",
"@odata.etag": "W/\"CQAAABYAAAAVnorvafscTKPg1Ow9cHJAAACpk/SK\""
},
{
"subject": "Major update from Message center",
"id": "AAMkAG...vAAA=",
"@odata.type": "microsoft.graph.message",
"@odata.etag": "W/\"CQAAABYAAAAVnorvafscTKPg1Ow9cHJAAACpk96l\""
}
]