The WP-EMail WordPress plugin before 2.69.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)
https://wpscan.com/vulnerability/3f90347a-6586-4648-9f2c-d4f321bf801a