MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
GetResponse - Email marketing from GetResponse. Send email newsletters, campaigns, online surveys and follow-up autoresponders. Simple, easy interface. FREE sign up.
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
ActiveCampaign - Integrated email marketing, marketing automation, and small business CRM. Send beautiful newsletters, setup behavioral based automations, and benefit from sales automation.