Hi, using windows client, can’t log in to outlook! Display password verification error
In mid-2024 Outlook.com had stopped accepting plain passwords from mail apps (Microsoft’s Basic Auth shutdown), which is why the password check failed even with the right password. Mailspring 1.14.0, released a few months after your post, moved Outlook.com / Hotmail accounts to Microsoft’s sign-in page in your browser (OAuth) — so on a current 1.24.x build there’s no password to type into Mailspring at all.
Update, then Preferences > Accounts > + > Outlook.com / Hotmail, sign in on the Microsoft page that opens, and you’re done: Adding an Outlook.com, Hotmail.com, or Live.com account — Mailspring Documentation. If Microsoft reports an IMAP or SMTP error after the sign-in succeeds, check that “Let devices and apps use IMAP” is on in Outlook.com’s Settings > Mail > Sync email (Connecting to Microsoft Office 365 and Outlook.com — Mailspring Documentation), and if Microsoft itself is blocking the login with a security challenge, I'm getting "Invalid Credentials" when connecting an Outlook.com account — Mailspring Documentation shows how to clear it.