Back Up Emails

Outlook 2013:
http://office.microsoft.com/en-in/outlook-help/export-or-back-up-messages-calendar-tasksand-contacts-HA102809683.aspx

Outlook 2010:
http://office.microsoft.com/en-in/outlook-help/export-outlook-items-to-an-outlook-data-filepst-HA102534110.aspx

Outlook 2007:
http://office.microsoft.com/en-in/outlook-help/export-outlook-items-to-a-personal-folders-filepst-HA102538007.aspx

Apple mail:

Extracted from: http://support.apple.com/kb/ht2980#mail

To manually back up Mail messages (emails)

To back up entire mailboxes (where Mail stores messages), such as your Inbox, follow these steps:
1. Quit Mail if it's open.
2. From the Finder's Go menu, choose Home.
3. Open the Library folder.
4. Copy the folder "Mail" to your backup location, such as a different volume or burnable disc.

Important: Do not remove the Mail folder from ~/Library. If you're backing up to the same volume, hold the Option key as you drag the folder to make a copy instead of moving it (a "+" cursor appears).

ThunderBird:

Copying Mail to a Local Folder

1. Create new folder locally
- To copy e-mails locally you must first create a local folder.
- In the left pane of the Thunderbird window select Local Folders.
- Go to the File menu, click New, and then click Folder.
- Next, Assign the folder a name, and then select Local Folders
- Click on the OK button to create the folder.

2. Move e-mail to new local folder
- Now, select the e-mail messages that you wish to move offline and have saved in your local folder.
- Once selected (highlighted), right-click on the PC or Control+Click on the Mac and select Copy To,
- Then select Local Folder, then select the new folder.

OR

Install the following Addon in Thunderbird and restart the client.

https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

In thunderbird client, right click on the account , click ImportExportTools , select "Export all the folders ( with structure )", select OK.