You can send out gift tickets from the organizer platform.

Add a free ticket in the Tickets menu, and go to Advanced settings. Then go to Sales channel and untick the "online" box. Now only the "organizer" box is active and the ticket won't be seen to online customers.

Go to your profile and choose Settings, then Promoters. Choose your own promoter user and make sure that "cash" is allowed as a payment method. Then go to Settings and make the free ticket available to the user.

Go to the organizer platform and log in. Add as many tickets to the free ticket type as you wish to send out to an email address and the go through the purchase process. Enter the recipient's name and email address and choose "cash" as paymanet option. This way you won't be redirected to the online purchase platform, and since the item us free, no invoice will be generated.
Repeat this process for every email address you would like to send the gift tickets to.