There is a great post made by Yana regarding the CRM email integration - unfortunately I was unable to find it again to put the URL here. Hope it is still current.
Anyway, the post was translated to Portuguese and can be found here: http://www.radsolucoes.com.br/pt-BR/bitrix24-faq I also created a flowchart diagram that makes the process very easy to understand. If you want to create new leads automatically this is the way to do it. By the way: Lead-attached business process ARE started by the new lead creation...so you may created tasks, send IM, emails, and all the good stuff that workflows are known for!
Attached is the English version of the diagram. Enjoy!