Email Archiving is the act of preserving and making searchable all email to/from an individual. Email archiving solutions capture email content either directly from the email application itself or during transport. The messages are typically then stored on magnetic disk storage and indexed to simplify future searches. In addition to simply accumulating email messages, these applications index and provide quick, searchable access to archived messages independent of the users of the system using a couple of different technical methods of implementation. The reasons a company may opt to implement an email archiving solution include protection of mission critical data, to meet retention and supervision requirements of applicable regulations, and for e-discovery purposes. It is predicted that the email archiving market will grow from nearly $2.1 billion in 2009 to over $5.1 billion in 2013.[1]

Definition

Email archiving is an automated process for preserving and protecting all inbound and outbound email messages (as well as attachments and metadata) so they can be accessed at a later date should the need arise. The benefits of email archiving include the recovery of lost or accidentally deleted emails, accelerated audit response, preservation of the intellectual property contained in business email and its attachments and “eDiscovery” in the case of litigation or internal investigations (what happened when, who said what).
Overview

Email Archiving is the process of capturing, preserving, and making easily searchable all email traffic to and from a given individual, organization, or service. Email archiving solutions capture email content either directly from the email server itself (journaling) or during message transit. The email archive can then be stored on magnetic tape, disk arrays, or now more often than not, in the cloud. Regardless of the location of the email archive, it gets indexed in order to speed future searches, and most archive vendors provide a search UI to simplify query construction.

In addition to email, attachments and associated metadata, some email archiving applications can also archive additional aspects of a mailbox including public folders, .pst files, calendars, contacts, notes, instant messages and context.

Objectives of Email Archiving

There are many motivations for enterprises or end-users to invest in an Email Archiving solution, including:

Data Preservation
Protection of Intellectual Property
Regulatory compliance
Litigation and Legal Discovery
Email Backup and Disaster Recovery
Messaging System & Storage Optimization
Monitoring of Internal & External Email Content
Records Management (Email Retention Policies)
Business & Email Continuity

Read more at http://en.wikipedia.org/wiki/Email_archiving