[Ayantir]

local function ChatMessageChannel(messageType, fromName, text)
    
    if messageType == CHAT_CHANNEL_WHISPER then
    
        -- Don't zo_strformat UserId's
        local pstPerson
        if string.find(from, "@") == nil then
            pstPerson = zo_strformat(SI_UNIT_NAME, fromName)
        end
        
        d(pstPerson)
        
        if (IsFriend(pstPerson)) then
            d("A friend just whispered you")
        end
        
    end
    
end
 
ZO_ChatSystem_AddEventHandler(EVENT_CHAT_MESSAGE_CHANNEL, ChatMessageChannel)

I didn't checked it, but it should work as intended, no?