WP Email Delivery VS Postal

Sidemail - The simplest way to send transactional emails. Sidemail makes sending transactional emails trivial, it's perfect for side projects, MVPs or the next big thing.

Mailook - Identify & fix your email deliverability issues for free 👀

Mailivery - Reach the Inbox, not the spam folder.

PromoTab - This tiny tool uses a real Gmail account to check if your emails will land in the Primary inbox of a reader or if it's stuck in the promotions tab or SPAM folder.

YaySMTP - WordPress Mail SMTP

The Sales Email Deliverability Guide - An in-depth guide to understanding email deliverability and how to improve it.