Respondable | Boomerang for Gmail vs Shortwave

Respondable is an email assistant built into Boomerang for Gmail that scores drafts as you type. It predicts how likely a message is to get a reply and explains which factors drive that score, drawing on patterns from millions of sent emails. The tool surfaces tips on tone, including politeness, positivity, and subjectivity, so you can adjust wording before hitting send.

Most Gmail users guess at tone and hope for a response. Respondable gives live feedback inside the compose window instead of waiting for silence. That makes it especially useful for outreach to clients, follow-ups with your manager, and any thread where a missed reply costs time.

Sales reps, recruiters, and anyone living in Gmail who needs higher reply rates are the core audience. Respondable ships as part of the Boomerang extension, which also covers send-later, reminders, and inbox pause. Boomerang reports more than 1 million businesses on the platform and SOC 2 Type 2 certification on its main site.

Shortwave is an AI email client built by former Google engineers that wraps Gmail with inbox organization tools and an agent you can prompt to search, write, schedule, and filter mail. It runs on iOS, Android, Mac, and Windows and syncs with Gmail accounts. The app positions itself as a spiritual successor to Google Inbox, with bundles, splits, and keyboard shortcuts at the center of daily triage.

Most Gmail add-ons bolt on one feature. Shortwave treats the whole inbox as a workflow surface: you triage with bundles and todos first, then ask the agent to draft replies, run natural language search across years of mail, or spin up filters written in plain English. That combo of Inbox-style organization plus a prompt-driven assistant sets it apart from Superhuman-style speed clients and basic AI summarizers.

Sales reps, founders, and support leads use it to split high-priority threads, track read receipts, and share live threads with teammates without pasting screenshots into Slack. Teams on Gmail who miss Inbox bundles or want calendar-aware scheduling from inside mail tend to stick with it once they adopt the Shortwave Method triage flow.