In case you sign a contract or any other document with another contracting party via e-mail, each party is concerned about the authenticity of the identity of the person that sends the document. Each party is also concerned about the integrity of the document. The document might have been altered from the time it was sent until its receipt.
To alleviate these problems and to avoid any forgery of signature or alteration of the text content, the personal digital certificate has been established. By sending a digital certificate, the sender can send encrypted messages that only the addressee of the message is able to decode. The digital certificate belongs to the Public Key Infrastructure ( PKI ) , ie. a system in which is created , used and / or canceled for both users and ISPs.
Digital certificates are based on the concept of a private and a public key. The public key of a user is available to any other user in the simplest form, i.e. when it is not encrypted. On the other hand, the private key is secret and protected with a personal password. The personal digital certificate is installed in the browser after being obtained from the appropriate site. The person installs to the computer, the program of e-mails management. Then the system is used automatically for example when the user is asked to sign an e-mail.
When the certificate is installed and the appropriate arrangements have been made, then, there is a default signature in the user’s e-mails. Users of personal digital certificates should choose the same Certification Authority that will be trusted for both parties so there are no differences, problems or differentiation in its fairness in relation to the parties (the sender and the receiver of the e-mail).
The digital certificate provides authentication of the computer hosting the site, and encrypted communication between your computer and the site to which the user navigates. When you see a site that has in the browser the https and there is a locked padlock icon in the browser, then you understand that there is a digital certificate on this site and then you can feel safe about your navigation.
Thus, yes there is a way to sign a contract and send it via E-mail but be certain that both parties choose the same Certification Authority.
Source: yellow talk, Malta