A combination of an S/MIME-Certificate and an SSL/TLS-Certificate doesn’t exist for the reason that they serve drastically different purposes.
An S/MIME-Certificate secures the encrypted conversation via e-mail. Therefore it prevents an involuntary flow of information to third parties and secures the electronic correspondence with customers and business partners.
An SSL/TLS-Certificate encrypts the transport path between server and client. This means that all traffic such as transferred passwords between the website and server are safely encrypted.
For the reasons mentioned above a combination of both certificates isn’t possible. For further consultation about your portfolio and support in the search for new certificates you may call our support team under the phone number: +49 661 480 270 10.