Blocked for Gravity SMTP

In a weekly report I see this blocking information on my several websites: “Recently Blocked Attacks: Gravity SMTP <= 2.1.4 – Unauthenticated Sensitive Information Exposure via REST API” or “Blocked for Gravity SMTP <= 2.1.4 – Unauthenticated Sensitive Information Exposure via REST API in query string: rest_route = /gravitysmtp/v1/tests/mock-data” But this plugin not installed on my sites! How can I solve this problem? Thank you!