Never load images in emails 😘

I think the best way is to disable loading of external content in your email client, but I'm not 100% sure.

I think Thunderbird by default does not load external content. Mine always warns me whether I want to allow for remote content when I open a new email, and possibly whether I want to always allow it for a particular sender. I never do.

Check the settings, and possibly reset that option.

Set your client to not download/show embedded images, so only the text part gets loaded.

I have all of my email clients set to not load internet content. Probably why one of my banks, Navy Federal, keeps saying my email address is invalid despite the fact I get their emails.

Most email clients don't fetch remote resources like images embedded in emails unless you specifically ask them to. If you're seeing pictures in your emails without having to tap something extra after opening the email, you likely need to change your settings.

As someone else pointed out, FairEmail for android additionally blocks tracking pixels even if you want to load other images.

Loading other images or resources can still track you. For example, rather than using a tracking pixel, a company could create (let's be honest, generate 🙄) a unique image for each email campaign they do, and make that a visually important part of the email, such as a title banner, and then track who loads that to see who opened the email. They could even add tracking metadata to the URL like https://example.com/email-resources/october-newsletter-header.jpg?user=your-email%40your-domain.com

FairEmail shows these kind of pixels very obviously and gives customisation options too.

Email aliasing services, which are genuinely good services to use, strip those pixels from inbound emails. At least Firefox Relay, Addy and SimpleLogin do

They only load if you load images, every email client I've used does not load them by default for this reason.

You can also run an DNS adblocker like Adguard Home or PiHole and that will block a lot of the domains commonly used for tracking pixel images.

How does it work? Like a read receipt? I thought the likes of thunderbird were essentially offline after initial loading?

I view all my emails as plain text, no html.