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Email Formats

The term email started as an abbreviation for electronic mail when correspondence was primarily in paper and electronic types of activities tended to be a name with an “e” in front. Email in South Carolina government is considered correspondence and treated the same as physical mail correspondence and memos. Based on the policies set by the archives and state government, email is either kept for permanent preservation in SCERA, printed out in paper copies, or destroyed. More often than not, emails that have been destroyed are internal correspondence that do not have any permanent value. For example, an email between coworkers about where to eat lunch on Tuesday does not have enough value showing how an agency works to justify permanent retention.

File types

Email is an electronic message sent between servers in a text format. It can have embedded images, as well as attachments that can be separated off (such as a .pdf file). Email comes in a variety of formats, but for SCERA there are usually only two: .eml and .msg. Less common formats include mbox, which will not be discussed here.


The .eml format is the Internet Message Format. It is a structured file that includes the text of the message and any of the files attached to the message. Email sent to, or received from, a .eml-based email client program is format neutral and can be viewed by any email program. Once received by the .eml-based program the individual email is saved in the .eml format and requires a program designed to read that file type. Mozilla Thunderbird is a common .eml-based email client program. Although it does not save in this type of format, Microsoft Outlook 2010 is capable of reading .eml files.


The .msg file format is the proprietary format used by Microsoft for email. The most common computer program that uses .msg email files is Microsoft Outlook. Email sent to, or received from, a person using Outlook is format neutral and can be read using any email client program. BUT, once in Outlook it is saved as a .msg file and cannot be read using most other email client programs. Any files attached to the email are saved within the .msg file.


The .pst file format is the Microsoft answer to handling too many old emails. A .pst file is an archive-type file that holds all the emails a user puts into it, including attachments. The contents of a .pst can be loaded by Outlook or explored using certain types of software designed to read a .pst file. The .pst file keeps the folder structure of the email inbox of the person who made the file, so exploring a .pst file is similar to exploring how the creator managed their information.

Programs for accessing email

Email is most often accessible in two ways: through an internet portal or through an email client program.

An internet portal, such as Gmail and, converts a email message to a html page for viewing and requires a user to have a html browser program. This is convenient, but requires the email user to have online access any time they want to access their email.

An email client program is installed on a computer that can download and send email messages from the internet using rules specific to emails, and allows users to look at downloaded messages while offline. Messages can be manipulated in an email client program in ways that are not possible with access through an internet portal. Messages a general public user can access via the internet using an email service can usually also be downloaded using an email client program.

The most common email client program on the market (as of 2015) for office productivity is Microsoft Outlook, which saves messages in the .msg file format (see above description of .msg files).

A common, and open-source, email client program that uses the .eml format is Mozilla Thunderbird.

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