I am sending emails with Nodemailer, furthermore I use the ical-generator package to generate .ics files, these files are visible as an attachment in the email I sent, but there is no button which display an instant action to accept the invitations like some other mails show.

This is my current implementation:

export default function generateIcal(req, res) {
    const generatedEvents = req.body.data.map(d => ({
        start: new Date(d.date),
        end: new Date(addDays(d.date, 1)),
        summary: req.body.summary,
        organizer: {
            name: 'Frodo',
            email: 'frodo@cool.com',
            mailto: 'jonwick@gmail.com'
        },
    }))

    try {
        const data = ical({
            method: "REQUEST",
            domain: "https://mydomain.de",
            name: 'test',
            events: generatedEvents
        }).toString();

        return res.status(200).json({ data })
    } catch (error) {
        return res.status(error.statusCode || 500).json({ error: error.message });
    }
}

This is how I use Nodemailer in that case:

  try {
    let info = await transporter.sendMail({
      sendMail: true,
      from: sender, // sender address
      to: req.body.email, // list of receivers
      subject: `test.`,
      text: 'test',
      icalEvent: {
        filename: 'invite.ics',
        method: 'request',
        content: calContent // content generated above
      },
    ```