GlockApps - G-Lock Apps is an interesting tool that might seem simple to some, but is quite essential to most online marketers.
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
dmarcian - Safeguard your email from abuse
Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.
Vetter - An online suggestion box for employees
Email Kick - Email designer and analytics for your transactional emails.