Add to calendar in a newsletter
Email is the highest-value place for an add to calendar link and the most restrictive. Every fancy widget you find is JavaScript, and every email client strips JavaScript. What is left is plain links, which is enough if you build them properly.
Use the HTML snippet, not the widget
Gmail, Outlook and Apple Mail all remove <script> tags before rendering. A dropdown widget therefore shows up as nothing at all, or as a bare unstyled div. Use the HTML snippet instead: anchor tags with inline styles, which is the only styling email clients agree on.
One line, five links, no dependencies:
<div style="font-family:Arial,sans-serif;font-size:14px;">
<strong>Add to calendar:</strong>
<a href="https://calendar.google.com/...">Google</a>
<a href="https://outlook.live.com/...">Outlook</a>
...
</div>Where to put it
Directly under the confirmation sentence, not in the footer. The moment someone reads "you are registered" is the moment they will act, and every scroll between that sentence and the link costs you attendance.
In a reminder email a day before, put it at the very top. People opening that email have already forgotten whether they added it.
Per-platform notes
- Mailchimp. Paste into a Code block, not a Text block. The text editor rewrites inline styles.
- Brevo. Use the HTML widget. Turn off link tracking on these links, or Brevo wraps them in a redirect that some calendar apps refuse to follow.
- Klaviyo. Works in a Text block, but check the preview: Klaviyo sometimes appends UTM parameters that break the calendar URL. Add the links to the tracking exclusion list.
- HubSpot. Use a Rich text module in source mode.
The link-wrapping issue is the one to watch across all of them. If your test event lands in the calendar with a title like "Click here to continue", the platform rewrote the URL.
Measuring whether it worked
Your email platform will tell you the link was clicked. It cannot tell you the event was actually saved, and it cannot tell you which calendar people use, which is genuinely useful for deciding what to put first next time.
Switching on click counting routes the links through this tool first and gives you a per-calendar breakdown, with no cookie and no consent banner. If most of your list turns out to be on Outlook work accounts, that changes what your button order should be.