First, the housekeeping: [Notion](/entry/notion-versus-readwise-which-subscription-actually-fuels-your-knowledge-workflow) Mail is shutting down in September 2026, so if you were considering it as the cheap option, that door is closed. This is Superhuman vs Shortwave now, and neither is cheap.
| Entry price | Works with | Free plan | |
|---|---|---|---|
| Shortwave | Business $30/seat/mo ($24 annual) | Gmail only | no — 14-day trial |
| Superhuman | $40/mo ($33 annual), Business plan only | Gmail and Outlook | no |
Superhuman costs $40/month and, as of 2026, is only sold on the Business plan — the standalone consumer tier is gone. What you pay for is speed: a keyboard-driven interface engineered so that experienced users clear their inbox measurably faster, plus AI drafting and triage. It supports both Gmail and Outlook.
Shortwave starts cheaper at $30/seat (Business), scaling to $45 and $120 tiers, and it's Gmail-only. Its angle is AI-native email — an assistant that can search, summarize threads, draft replies and organize your inbox with more depth than Superhuman's AI, built around Gmail's data model.
The honest question is whether any email client is worth $30–40/month. For most people the answer is no — Gmail plus a few filters plus one of the free AI assistant extensions gets you 80% of the value. The people for whom it pays: those who live in email all day, where a 20% speedup on hours of daily work genuinely compounds, and who'll actually learn the keyboard shortcuts (Superhuman) or lean on the AI (Shortwave).
On Outlook, or you want the fastest keyboard-driven inbox: Superhuman. On Gmail and you want the deepest AI assistance: Shortwave, and it's $10 cheaper. Not sure email is your bottleneck: it probably isn't — skip both.