Apple Mail - HTML Signatures

Hi All,

Have an issue with my Apple Mail client when using it for my work account. Whenever I send an email via Apple Mail, the HTML signature that automatically gets applied to the footer of the email is turned into text and doesn't display correctly for the recipient. Whenever I send an email via the same email account, but using any other email client it works fine. The signature is being applied by a service similar to CodeTwo, meaning it is applied by the server not the client. However this issue only occurs when using my work mail from Apple Mail.