See how sendgrid compares to other vendors in security performance
The SMTP for SendGrid – YaySMTP plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 1.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
The SendGrid WordPress plugin is vulnerable to authorization bypass via the getajaxstatistics function found in the ~/lib/class-sendgrid-statistics.php file which allows authenticated users to export statistic for a WordPress multi-site main site, in versions up to and including 1.11.8.