MDaemon Email Server 17.5.1 allows XSS via the filename of an attachment to an email message.

MDaemon Email Server 19 through 20.0.1 skips SpamAssassin checks by default for e-mail messages larger than 2 MB (and limits checks to 10 MB even with special configuration), which is arguably inconsistent with currently popular message sizes. This might interfere with risk management for malicious e-mail, if a customer deploys a server with sufficient resources to scan large messages.