Yes it is feasible to get the item id from the return result. You just need to add the itemid
in the field projection. Please see below the updated Rest API
http://{host}/sitecore/api/ssc/item/search?term=12345&includeStandardTemplateFields=False&fields=Email,itemid
I did a small test with the home item and the result are shown below (which returns the item id from where it got the result)
REST API
http://{domain}c/sitecore/api/ssc/item/search?term=home&includeStandardTemplateFields=False&fields=itemid,title
Response
{
"TotalCount": 2,
"TotalPage": 1,
"Links": [],
"Results": [
{
"ItemID": "8e18ac80-0084-4859-8df4-d8a2fffa5f3b"
},
{
"ItemID": "110d559f-dea5-42ea-9c1c-8a5df7e70ef9",
"Title": "Sitecore Experience Platform"
}
]
}
More information can be obtained from the Sitecore Documentation - The ItemService.
In the section ItemModel return values, it shows what are the different values that it returns. You just need to specify them in the field projection.