Classic Outlook is drawn by Microsoft Word on this PC, the engine that app uses. Every other view is a simulation in this browser: the email is changed the way each app is known to change it, and dark mode is drawn by recoloring. The apps don't publish their rules, so treat the dark views as a strong hint and still open one real test on a phone in dark mode before a big send.
Checks run by themselves: links and pictures are opened, spelling and grammar are checked on this PC (Harper, then Word as a second opinion), and the words inside pictures are read with Windows' text recognition. Rules live in rules.json and dictionary.txt in the tool's folder.
Keys: 1–8 pick an app · A all apps · D dark · P phone · L light and dark side by side · [ and ] previous and next email · Ctrl+click a link in the preview to open it.
This is the hosted version: exports are read in your browser and never uploaded unless you share them for review. The classic Outlook view, Word's second opinion and reading the words inside pictures need Windows and Word, so they are only in the PC version.
Email Preview © 2026 Aaron Williams. All rights reserved.