How can I add a calendar invite to my campaign emails?

How can I add a calendar invite to my campaign emails?

I use Zoho Campaigns to attract prospects to a series of webinars that we run.

I have a general pool of contacts that I campaign to, and I have them join a new list for the specific webinar they wish to join.

What I would like to do next is send an email to those that want to join a webinar, with a calendar invite that they can accept to add to their Outlook calendars (containing the URL and details of the webinar).

How can I do this?