Taking backup of mail account :
There are two options to create backup of your mail Archiving and making .pst file outlook ( Preferred over archive option ).
1. Log in to Gmail
3. Accounts Tab
4. Google Accounts Settings (this will open new page)
5. Data tools (From top pane)
6. Download Data (Right corner)
7. Select Mails (From various option )
8. Next ( At Bottom page)
9. Create archive
This will create archive and send link to your account.
That will download archive in MBOX format.
2. Outlook configuration with POP protocol
This will create .pst file on your pc.
Ports for configuration
Port No. 995 SSL enabled
Outgoing Mail Server:
Ports: 465 SSL Enabled or Port no.: 587 TLS enabled