Attack sim phish email pictures not showing up

Question

When I send out an attack simulation with images in the payload and a made up email as the sender the images say "Right-click or tap and hold here to download.. etc.."
If I use an actual email in our domain as the sender the images in the email are there. Is there a potential work around for this? I suppose I could add the made up email to our safe sender list but that seems like a real pain to do everyweek. What is the typical preference or workflow for senders when creating a payload?
I don't want to use an actual email within our organization either because in the case say we use HR@randomdomain if a user has an autoreply HR gets these random auto replies from users. Am I missing something here?