Microsoft Exchange Server
Exchange Origin
Sample Origin Filters
Query strings in the EWS Managed API and EWS are interpreted as a subset of AQS syntax. AQS strings are composed of either values or keyword/value pairs, separated by a colon (:).
keyword:value
When a value is specified without a keyword, all indexed properties are searched for the value. If a keyword is paired with a value, the keyword specifies a property to search for the corresponding value.