I receive a lot of newsletters and communiqués, some of which I even signed up for. So, I don't know what designers use to receive e-mail, but here in the non-designer / non-linux world, Outlook is pretty popular. Now, Outlook - at least all configurations I have seen, has pictures via HTML disabled. I have sampled a few IT departments only, of course, but I feel like this is probably a pretty common policy. So let m…
Outlook is probably the most common desktop client, but I think most people (even in corporate settings) are using webmail these days; either Google Apps Suite or Office 365. The former at least displays images by default (Google re-hosts them and rewrites the email source). Not sure if MS does the same.
My messages still don't load remote images and are topped with "Some content in this message has been blocked because the sender isn't in your Safe senders list" followed by a link to add the sender's address to the trusted list and another link to show blocked content in this particular message.
I have Apple's Mail desktop and mobile apps set to not load remote content but I think the default is for them to load.