In recent years, many regulations about email for commercial communication have came into force in varies countries. For example, Germany has laws requiring companies to disclose their company name, registration number, place of registration etc. in e-mail signatures. Ireland's Director of Corporate Enforcement requires all limited companies operating websites to disclose such information in their emails. The UK's ECommerce Regulations require this information in all emails from limited companies as well. While criticized by some as overly bureaucratic, these regulations only extend existing laws for (paper) business correspondence to email. Any infringement to these regulations will result in lawsuits.
Even if your country has no similar regulation, it is still worth to append an email disclaimer in every email as in some situations it may protect you from liability in a court of law.
Implementation of Disclaimer or email digital signature can be done on client side. A simple way is to ask your employee to have disclaimer/digital signature set in their email clients. However, this method is lack of flexibility and there is no way for a company to verify if a disclaimer was added and its content is correct.
With EA Disclaimer, S/MIME tool, instead of end user, server administrator sets disclaimer, digital signature for each user on server side. This greatly adds fexiblitiy and controllability to your company and simplify the task. Moreover, thanks to digital signing capability of the tools, outgoing emails will be avoided to be moved to junk folder of Hotmail, Gmail and Yahoo mail.