Hey there @Toradex70328 - thanks for your post!

Here’s what I suggest: 

• Have the user check their spam folders
• Have the user search their email for emails from notifications@calendly.com
• Have the user allow our IP addresses - update your firewall or security settings to automate the inclusion of our new IP addresses. The updated list of IP addresses can be found at this developer endpoint. Please review the list and update your firewall settings where necessary to avoid any disruptions to your integrations with Calendly.

You will also want to double check that the invite is being sent to the correct email address, that there are no typos in what you wrote and so on. If these steps do not help, I suggest reaching out to our support team (available 24/7) for more individual troubleshooting. They will be able to dig deeper to find out what’s going on and reach a solution for you! You can do this by logging into your account and clicking “help.” Have a great day! =)