Tell me some best HTML email template providers?

I'm looking for an open source email builder which I can integrate with my current email service. Where will I get it?

Is there any place where I can get 100's of free email templates for different business niches?

I am using MailChimp for my email marketing service but i am not happy with the inboxing rate.Did any one tried Amazon SES for sending emails and how is there inboxing percentage?

I need IP's for sending bulk emails, Is there any way to get IP for sending bulk emails. I will do legitimate email marketing, less bounce and spam.

I want to connect external SMTP to send emails for WooCommerce, Is it possible to do it?I want to send payment receipts, cancellation payment notice, chain product info for WooCommerce?

Is it possible to connect external SMTP to connect in WordPress to send transaction emails?

I there any way to create a professional email signature that I can use in my Gmail, Yahoo, Hotmail when sending emails?

How much should be the “subject line length” in emails and does it matter?

What are outbound sales? How can I write these emails to get maximum open and click rate?

Does template emails are more effective than normal text emails?

Can social media act as a powerful medium for email marketing?

How can I get the free email hosting?

What are SPF & DKIM and why authentication of both are necessary?

Does video emails are more effective than the text emails?