https://localhost:403/ccm/oslc/users?oslc.properties=rtc_cm:emailAddress
or
https://localhost:403/ccm/oslc/users?oslc.select=rtc_cm:emailAddress

will return the user node with their email id

here is a sample output that i receive for https://localhost:9443/ccm/oslc/users?oslc.select=rtc_cm:emailAddress , for your reference:

<oslc_cm:Collection oslc_cm:totalCount="45">
   
    <rtc_cm:User rdf:resource="https://localhost:9443/jts/users/rm_user">
    <rtc_cm:emailAddress>mailto:unknown</rtc_cm:emailAddress>
    </rtc_cm:User>
   
    <rtc_cm:User rdf:resource="https://localhost:9443/jts/users/custadmin">
    <rtc_cm:emailAddress>mailto:bdineshkumar%40in.ibm.com</rtc_cm:emailAddress>
    </rtc_cm:User>
   
    <rtc_cm:User rdf:resource="https://clm40.in.ibm.com:9443/jts/users/bob">
    <rtc_cm:emailAddress>mailto:bob%40jkebanking.net</rtc_cm:emailAddress>
    </rtc_cm:User>
   
    <rtc_cm:User rdf:resource="https://clm40.in.ibm.com:9443/jts/users/al">
    <rtc_cm:emailAddress>mailto:al%40jkebanking.net</rtc_cm:emailAddress>
    </rtc_cm:User>
   
    <rtc_cm:User rdf:resource="https://clm40.in.ibm.com:9443/jts/users/curtis">
    <rtc_cm:emailAddress>mailto:curtis%40jkebanking.net</rtc_cm:emailAddress>
    </rtc_cm:User>
   
</oslc_cm:Collection>

If the email address is not configured for the user, it shows up as unknown against mailto as seen for the functional rm_user above.

hi Kevin,

I believe you have noticed the right parameter and you can append that to the query using an & (ampersand) and the parameter with a desired page size as its value, here is a sample:
https://localhost:403/ccm/oslc/users?oslc.select=rtc_cm:emailAddress&oslc_cm.pageSize=1000