RE-MAIL-CK
Remote Mail Checking Protocol (RMCP) is a mail checking service that is used between a client and a server pair. Client queries server in order to find out whether new mail has arrived for a specified user. The protocol provides for both non-authenticated and authenticated polling.
Available to all SRX running 12.3X48+
Available to all MX running 20.2R1+
Available to all vSRX running 20.3R1+