GlockApps - G-Lock Apps is an interesting tool that might seem simple to some, but is quite essential to most online marketers.
Hunter - Find all the email addresses related to a domain
dmarcian - Safeguard your email from abuse
Warmy.io - Auto all-in-one tool for email deliverability to make your Email Channel Reliable.
Vetter - An online suggestion box for employees
Maool Email Editor - Maool Email Editor : Create beautiful emails in less time with no coding knowledge.