Big red flag:<p>> The hash of an email is computed using the SHA2-512 hashing algorithm and signed with our own 512-bit private RSA key.<p>Why even bother signing it if your key is that weak?<p>Furthermore, they sign every message individually with the same key. This does not make sense to me: why not just sign the root of the Merkle tree?<p>Other fun stuff:<p>- They both supply email tracking, and protect your privacy by blocking email tracking...<p>- It doesn't prove that the email has been sent, it just proves that it has been submitted to Gmelius for signing.