Unfortunately, Mailspring does not support Exchange (Exchange Web Services or ActiveSync), nor do we plan to support this in the future. Presently, you may be able to connect to your Exchange server via IMAP. Note that not all Exchange versions support this feature.

If your organization uses Exchange Online / Microsoft 365, choose the Office 365 option when adding your account — Mailspring signs in with Microsoft OAuth and connects over IMAP and SMTP. Your administrator may need to enable those protocols; see Connecting to Microsoft Office 365 and Outlook.com.

For a full list of the providers Mailspring supports, see: Supported Email Providers