Before leaving home, let laptop, tablet, etc. update, and even receive all emails.
If it's a laptop that is not always used except for traveling, this is especially important. Then turn off Windows updating after updated till back at home.
If one has more than one device, just use one for emails. If more than one device is used, each one will be downloading the same emails.
Better yet, view your mail at your emails provider's site , ie. gmail at mail.google.com for example. Then just select what you want to read and reply to. If someone sends you an email with photos, now you have
the choice to view them later. You don't have to view or download what you don't what to until at home or in a location where it can be downloaded or viewed for free.