Exporting emails from Zoho mail to Local storage

Exporting emails from Zoho mail to Local storage

Hello,
My question is two
(1) Because of capacity issues, how do we take an back up of old emails onto the local folder, Can that be accessed later on from CRM or Zoho mail, as we do require to keep clients data for a while
(2) I have got my Zoho email linked to CRM so that the emails which are sent to them  or from them are visible in CRM. So if we copy it to an local folder, will they be visible in CRM or not? If not what are remedies other than paying and increasing capacity.

Thanks

Pradeep