Hey ​@Anton14521 - Thanks for reaching out! To clarify, are you the host of these bookings, or are you making the booking with another Calendly user?

For starters, I’d recommend white listing our sending IP addresses at 167.89.22.99, 149.72.200.43, and 149.72.248.16 and making sure that notifications@calendly.com is on your safe senders list. 

If this is already done, I’d recommend reaching out to our support team so they can look into any specific errors for your account.