Can a link to pay an invoice be added to an existing email system ?

Can a link to pay an invoice be added to an existing email system ?

   Can a link to pay an invoice be added to an existing email system ?

        My client has an existing MS Access system that generates invoices and emails them with Eudora   ( not my design; I’m picking up where the old programmer left off).

  I’ve been asked to allow credit card payment ( for the first time; my customer has no current method for accepting credit cards) . I’ve looked at Zoho quickly and now wonder if there is any method to add a link to the existing email that would allow the clients of my customer  to pay , using perhaps Stripe as the CC processor and the  Zoho API for the link in the email, .etc.

  In other words can I “tack on” an invoice system to the Eudora email ?  Or is what  Zoho offers as email only generated by  their system and sent from Zoho’s  server?

  ( Obviously this is a newbie/ early look kind of question; I’ve quickly scanned the help here but have not yet attempted to use the API.  I’m trying to save time by not going down a road I’m not sure yet will work.)