Mailspring supports the largest email providers. Supported services include:

• Gmail and Google Workspace (signs in with Google)
• Microsoft 365 / Office 365 and Outlook.com, Hotmail, Live, MSN (signs in with Microsoft — see connection notes)
• Yahoo (requires an app password)
• iCloud (requires an app-specific password)
• FastMail (requires an app password)
• GMX and Yandex (IMAP must be enabled in your account settings; Yandex needs an app password if you use two-factor auth)
• ProtonMail, via Proton Mail Bridge
• Any other IMAP / SMTP provider — choose IMAP / SMTP when adding the account. Mailspring knows the server settings for hundreds of providers (AOL, Zoho, mail.com, Posteo, 163.com, QQ, and many ISPs) and fills them in from your email address; you can edit anything before connecting.

While Nylas N1 had support for Microsoft Exchange, Mailspring does not support Exchange protocols. However, many Exchange providers will let you use Mailspring via IMAP.

Mailspring does not support connecting to accounts via POP / POP3. The vast majority of mail providers that support POP3 also support the newer, better IMAP standard. POP / POP3 support is not planned and will not be added in the future.