There are 2 open security issues in buster.
2 issues left for the package maintainer to handle:
OpenDMARC through 1.3.2 and 1.4.x, when used with pypolicyd-spf 2.0.2, allows attacks that bypass SPF and DMARC authentication in situations where the HELO field is inconsistent with the MAIL FROM field.
OpenDMARC through 1.3.2 and 1.4.x allows attacks that inject authentication results to provide false information about the domain that originated an e-mail message. This is caused by incorrect parsing and interpretation of SPF/DKIM authentication results, as demonstrated by the example.net(.example.com substring.
You can find information about how to handle these issues in the security team's documentation.