Cold Emailing Clients: Should You Send Image Attachments or Just Links?

Q:

When sending cold emails, is it better to include attached imagery, only links, or both? 

A:

I suspect (and have no actual proof), but my inclination is usually to send a link rather than images via email. I may be one of the few agents in the business to say this. Still, I suspect emailing our larger corporate clients’ image attachments will attract more firewall-stopping activity, preventing them from receiving our emails. What is your experience with this?