Merge Tokens don't render into actual values for CC fiel

Is this normal functionality or is this a bug? When we put merge tokens into the CC and BCC field of a Send Email trigger, the token does not get rendered into the actual value. Merge tokens only seem to function correctly in the "To:" field of send email triggers. See attached screenshot of the Audit Trail record of one of these email triggers. When putting a merge token in the CC field, we get an error "Transaction Failed: Missing final '@domain'"