It's not just their eMail Address, Telephone Number, Home and Work Addresses, as far as I can see that's not a problem, it's all the backup information that each Contact contains.
For example: My Power Company page has the consumption details for the last 4 years (had I not regularly truncated it, it could have held 18 years details. My friends Pages contain all their Children's birthdays, previous spouses, hobbies, foibles and useful notes about their lifestyle.
Now that I am retired, I've cut it down, from well over 1000 Individuals and Companies, to just below 500, but that's still a huge quantity of information that I don't want to loose.
Microsoft Outlook provides a feature called “Import or Export” and by using this option, you can export the entire database of MS-Outlook. You can export Outlook database (contacts) in various different formats like:
Even through Export option, user can save their crucial data into the external drive so they can use it in future.
For more about Export in MS-Outlook: *1***">[click here think, you should go with MS-Office as its one of the powerful email client application with tons of features.