There are many different platforms to sign emails from using an email signing certificate.

Please note that you cannot install an email signing certificte to a mobile device if the cert is intsalled to a secure token.

Windows Digitally Signing Emails

Here is a PDF tutorial for using the signing cert in Windows: PDF Document

Mac Digitally Signing Emails

Here is a PDF tutorial for using the signing cert in Mac: PDF Document

Android Digitally Signing Emails

Here is a PDF tutorial for using the signing cert in Android: PDF Document

iPhone Digitally Signing Emails

Here is a PDF tutorial for using the signing cert in iPhone: PDF Document