people don't seem to understand what pixel tracking is:
https://www.bbc.co.uk/news/technology-56071437
I use Mozilla Thunderbird as an email client on my PC,
it blocks remote content for my privacy and if I click on the options it displays the source url for each item of remote content it has blocked in an email,
I'm given the option to allow remote content from that source or continue to deny it,
even Microsoft uses tracking pixels in their emails, you're likely receiving a notification that I've posted this reply, in that email the tracking pixel is the 4 different coloured squares arranged in a square 'logo' that Microsoft uses,
when I block all content not in my safe senders and domains list I deny the loading of these tracking pixels, if the tracking pixel isn't retrieved from the senders server so that it can be displayed as part of the email the sender is unaware that I've opened the email,
because Microsoft has embraced pixel tracking technology and woven it into all of it's Office and email products it's created a huge problem for them,
spammers can use pixel tracking to see which of the emails they send are opened and hence identify 'active' email addresses, my guess is that they then focus on these addresses and also share them amongst other spammers,
the spammers are using exactly the same methodology to track their victims that Microsoft and the corporate community use to track their potential customers,
I've simply said: "enough is enough" and block all attachments, images and links not in my Safe senders and domains list,
this gives me a cloak of invisibility, I can open suspect emails, add the sender to my block list, report it as phishing to Microsoft and then delete it, all without the sender being aware I've even received it,
I've noticed that a week or so ago you couldn't select the option to: Settings>General>Privacy & Data>External Images.... option "Always use the Outlook service to load images"
I tried setting it to that option repeatedly but a save dialogue box would never appear to allow me to comfirm that setting,
now it seems to have miraculously set itself,
Microsoft seems to be forcing all remote content to be served via their Outlook servers so that they can try and monitor the pixel tracking content within emails,
so Microsoft do seem to be reacting to the problem, but secretively, they never seem to admit to any of their mistakes,