Hi Amy,
Unfortunately for Session emails you are unable to seelct an account user as an additional recipient. However, I will submit this as feedback to your product management team.
I have listed two alternative options that would notify an account user of what Sessions invitees are registered for.
1) If you are currently not using the CC email address field for your invitees, you could import the account user email into the CC Email Address field for all invitees if you are pre-importing invitations lists to send out invites from Cvent. Once the account user email is imported into the CC email address, you can go to Promotion & Communication>Session Emails>Click on Session Emails>Advanced Settings Tab>Edit>"Send a copy to the contact's CC email address:">Yes.
2) Another alternative is to use Planner Alerts. Planner Alerts notify you of different changes or developments during registration. If you go to Promotion & Communication>Planner Alerts>Create Alert>Category: Registration>Type: Registration Accepted>save>you will then be notified when invitees register and this alert contains the Sessions that invitees are signed up for.
Best,
Lauren