import { sp,  EmailProperties } from "@pnp/sp";

public onInit(): Promise<void> {
    return super.onInit().then(_ => {
      // establish SPFx context
      sp.setup({
        spfxContext: this.context
      });

    });
  }

const emailProps: EmailProperties = {
          To: ["test@myorganisation.com"],
          Subject: "This email is about...",
          Body: "Here is the body. <b>It supports html</b>"
        };

        sp.utility.sendEmail(emailProps).then(_ => {
          console.log("Email Sent!");
        });