GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!

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

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.

Sortd - Rated the #1 App for Gmail

VisualSitemaps - Visual Sitemaps | Crawl & Website Architecture + Flows

Email Architect - All-in-one system to write, manage and organize email