AOG
The best way to secure your mails is to back them up to a .pst file, and copy that file to an external drive, along with any other important documents you want to secure.
In fact, it's worth doing this on a monthly basis anyway, and is something that most people don't think about - but I've learned through painful personal experience, that losing all your mails can be a royal pain.
So to secure your Outlook mail (I assume that's your client), do the following:
1.On the File menu, click Import and Export.
2.Click Export to a file, and then click Next.
3.In the list, click Personal Folder File (.pst), and then click Next.
4.Click the folder that contains the messages you want to back up. If the folder contains a subfolder that you want to include, select the Include Subfolders check box, and then click Next.
5.Under Save exported file as, click Browse, and then specify a name and location for your backup file, for example, Mail Backup.
6.If you back up a .pst file that you have backed up to before, click one of the following:
Replace duplicates with items exported (Existing data will be overwritten with the information in the file being exported).
Allow duplicate items to be created (Existing data will not be overwritten, and duplicate information will be added to the backup file).
Do not export duplicate items (Existing data will be kept, and the duplicate information in the folder will not be copied to the backup file).
7.Click Finish.