How to backup mail in Win8.1 system

How to search, copy, archive and backup mail in mail application in Win8/Win8.1 system? Please refer to the following:
Find local folder where mail is stored
>All messages in the mail application are stored in the following location: C:UsersYour_UsernameAppDataLocalPackagesmicrosoft.windowscommunicationsapps_
XXXXXLocalStateIndexedLiveCommYYYYYZZZZZZ-ZZZZMail
Explain:
C:UsersYour_Username——This folder is the user's private folder, mail The application is hidden in a hidden folder AppData in this folder.
XXXXX and YYYYY are a string of random characters consisting of characters and numbers, ZZZZZZ-ZZZZ is a string of random characters composed of numbers, generally A 6-digit number and a 4-digit number connected by a hyphen.
Under the Mail folder, the settings and contents of each mail account are stored. A folder that will definitely be seen is a file named “1”. Folder, which stores the relevant content of the mailbox you are logged in. Other folders are the other files that are added. .
When you enter the folder, you can see a lot of files with the suffix .eml. These are the local mail contents. You can browse them normally by using Outlook or other mail client.

[Warning : Be careful when doing backup operations, because if you accidentally move, rename or delete these folders, it is very likely that the mail application will stop working and cannot be used. If you want to delete the mail, it is recommended to delete it from the mail application. Not directly deleted from the local folder.]
Browse/Find Email Information
You can use the search function that comes with Windows to search for the corresponding email information, not only search, but also search results in the order you want. Sort.
Enter an asterisk (*) in the search box to search all messages
See example:
modified:yesterday from:Helen
This search result will show all messages sent by Helen yesterday < Br>modified:2013 from:="Helen"
The search results will show all the mails that Helen searched in 2013
CC:Yoyo
This search result will show all the messages of all the copied Yoyo Content
BC C:Center
BCC is a Bcc, which contains the same meaning as CC
TO:Bob
This can search all the emails you send to Bob including reply emails
You can also search for others The email sent to you is also sent to Bob Mail="ABC.COM"
Exact search, mail header or text containing all messages of ABC.COM
Content:ABC
Inexact search, the word title or text contains the word ABC, or is searched as part of a word.
Backup save your mail
Create a new folder in any place you want to back up, Copy the mail you want to back up to this folder.
About the related issues in the system mail application, if you need it, maybe the above can help you.