Changing a text field to email field (across all records in the CRM)

Changing a text field to email field (across all records in the CRM)

Hi,

When I set up my CRM I made some emails fields simple text fields for some reason so it's simple text with no hyperlink. 

I'd like to change all of them so the hyperlink shows up that allows quick composition of emails.

Is it possible to change this now?  Or do I have to manually enter them all in again? (we have over 1,000 accounts)  

Thanks for the help.  

Aaron