Our startup, Invoiced, does exactly this. You can easily send invoices through our API [1] that customers can pay from the email. Now that Stripe ACH payments have been released we will be supporting it in the near future.<p>[1] <a href="https:&#x2F;&#x2F;invoiced.com&#x2F;docs&#x2F;api&#x2F;#send-an-invoice" rel="nofollow">https:&#x2F;&#x2F;invoiced.com&#x2F;docs&#x2F;api&#x2F;#send-an-invoice</a>