This article covers some of the issues involved when using a Digital Signature. Each Digital Signature is generated from a Digital Certificate (otherwise known as a Digital ID) issued by a certifying authority.
All examples given are created using Microsoft Outlook 2010 on a PC using Microsoft Windows 10, but the principles apply to other versions of Outlook and other email clients.
This article has been written to compliment my previous article Make Safe Financial Transactions.
Anyone using an Apple Mac can get appropriate certificate information in this article published by TechRepublic entitled: How to configure digitally signed email in Apple Mail.