It has been said above that your email is already a place where to archive but if you are looking for place outside Email inbox then follow what Foxpup says as google now are offering extra space in which we can safe place our Mails,photos Videos and everything that connects with our Data.
Thank you all for your suggestions. I am using a trial version of Mail Backup X to archive my mails and now I'm thinking of buying this tool.
https://www.mailbackupx.com/Well i don't Know what's the purpose of Buying a Mail buckup when Google offers for free,though if that is more safer and private volt then Better use that because Google has no good reputation in handling our Data.