Can I create leads, contacts, and organizations using incoming emails?

Yes. You can automate the creation of CRM records using emails coming into your mailbox. This is possible only when auto-forwarding is set up in your email client. Vtiger CRM uses email information to create deals, leads, contacts, organizations, cases, and other records when you set up auto-forwarding in your email client and mailroom rules. 

You can access the mailroom by going to Settings > Automation > Mailroom.