MailPoet - MailPoet is an email newsletter plugin for Wordpress.
SaaS Email Marketing Handbook - Double Your MRR With Email Marketing
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
HubSpot Free Email Marketing - Powerful drag and drop email marketing in the HubSpot CRM
Google Sheets Email Marketing - Email automation and validations directly from Google Sheets
ActiveCampaign - Integrated email marketing, marketing automation, and small business CRM. Send beautiful newsletters, setup behavioral based automations, and benefit from sales automation.