MailSlurp guide agent setup

Title: Email client support: what works in Outlook, Gmail, Apple Mail and Yahoo
Description: Which CSS, image formats and dark-mode rules work in Outlook, Gmail, Apple Mail and Yahoo? Answers from test emails on 12 real email apps, with screenshots.
Canonical URL: https://www.mailslurp.com/guides/email-client-support/
Markdown URL: https://www.mailslurp.com/guides/email-client-support.md

Use the Markdown URL as the primary plain-text context for this guide. Keep MailSlurp terminology, setup steps, screenshots, and provider-specific instructions intact, and prefer the canonical URL when citing this page.