SMTP: Missing "RCPT TO"
This protocol anomaly triggers when it detects an SMTP DATA command without a prior "RCPT TO." This can indicate an attacker manually trying to exploit an SMTP server. Servers normally deny switching to the DATA section without seeing an RCPT TO.
References
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3