Hey there, @Kristel54070 -  thanks for your question! Firstly, check out our New User Guide - it’ll def prove helpful as you get used to the platform! You’ll also want to check out the Company Admin Guide. 

For some context, with Calendly, there are two types of notifications: Email Confirmations & Calendar invitations.

1. With Email Confirmations, Calendly sends the invitee an email notification from notifications@calendly.com and has a reply-to address that's associated with your Calendly login email. You can modify this on Account Settings page.
2. With Calendar Invitations, your connected calendar sends the invitee a notification of the booked meeting which has a reply-to address that's associated with your Add to calendar email on your Calendar Connection page.

Note: Calendar invitations are not compatible with iCloud Calendar or the Outlook Plugin (for Windows users). Users with either of these calendar connections set up as their "add-to calendar" on their Calendar Connection page will be defaulted to Email Confirmations. 

One of these must be selected for each event type set up in your Calendly organization. There is no way to turn off both options. Your invitees will always receive either an email confirmation or a calendar invitation when booking. However, if you’d like to avoid sending emails from your internal email addresses to external recipients, just choose “email confirmations” instead of “calendar invitations” and this will result in all confirmations coming from notifications@calendly.com - not your internal email addresses! Keep in mind the reply-to email address in this case will be the login email address each individual host uses. I suggest considering the creation of email addresses specifically for Calendly to work around your issue, if that might help. Alternatively, using calendar invitations results in the invites being sent from your connected add-to calendar - in this case, creating calendars specifically for Calendly might also suffice as a workaround. I hope this helps!