Accepting Quotations


I would like to send an email with a PDF of a quote attached, which contains the following text:-

"Dear $customer,

Please find attached quotation as requested. To accept the quotation please visit and enter the following code:


I know the event module has something similar, but i would like to add a Code so that the user has to manually enter it to accept the quotation. I then hope to create w workflow to turn the accepted quote into a contract.

How should i go about doing this?

Many thanks