Missivus for WordPress

The same model as Missivus for Matomo — Microsoft Graph, application permissions, one free shared mailbox — for everything WordPress sends.

Why another Office 365 mail plugin?

Because today, the realistic WordPress option for Microsoft 365 is a paid extension built on delegated authentication — it signs in as a person and sends as that person. That has three costs the application-permission model does not have.

• Mail goes out as an individual mailbox, not your company's no-reply address — and when that person leaves, mail from your website stops with their account.
• The delegated token has a person's reach. An application access policy cannot save you — that mechanism only constrains application permissions, not a signed-in user.
• The Office 365 transport is the paid tier. Missivus for WordPress will be what Missivus always is — free, GPLv3, and scoped by Exchange to one shared mailbox.