ODMR
On-Demand Mail Relay (ODMR) is an SMTP extension that allows e-mail to be relayed once the recipient has been authenticated. It uses the Extended SMTP (ESMTP) command ATRN, similar to the ETRN command but available for dynamically assigned IP addresses.
Available to all SRX running 12.3X48+
Available to all MX running 20.2R1+
Available to all vSRX running 20.3R1+