We have been busy last few days incorporating estimate workflow into the product. If your business is based on receiving approval from your client, then this is just the perfect solution for you. This is how it works.
First and foremost, give your customer the portal access. This can be done on the "Edit" screen for that client. The contact information is used for setting up the client portal. A password is generated for your customer. This enables the customer to review all your communication with them, via a single portal, designed just for them.
Go ahead create an estimate with all the necessary data. And yes, you may include attachments or any additional information as documents. You may then "Save and Submit". Submitting your estimate, makes the estimate eligible for review by your client. As soon as you submit the quote, the quote is available in the "Pending Approval" queue of your client.
The client can then review the estimate and based on their discretion, approve or reject the estimate. A section for the reason for approval or rejection is also provided. An email will be sent out on approval or rejection so you can get notified immediately. Saving you time and money.
Once approved, you may proceed with your work and go ahead convert that approved estimate into an invoice just with the click of a button.