The providers of mass email accounts are increasingly using automatic spam detection on their servers.
This is done using a variety of mindless algorithms that are allowed to decide, but are rarely checked for their suitability and value for the user.
Email programs such as Thunderbird sort out spam anyway. And this without the presumptuous censorship of an email provider.
The reasons for this are primarily to keep their own server load low by avoiding millions of emails of junk, and less for the benefit of the user, as is often sold to them. However, these providers like to downplay the fact that this forces patronizing and even censorship on the users of email accounts. The providers mentioned above have often attracted unpleasant attention in the past, particularly when it comes to receiving emails.
The user believes that he can communicate with the world without restrictions and thousands of them become willing victims of dependence on gmail & Co. every day.
The mechanisms used are comparable to a little goblin who sits in the post office and can decide which letters the recipient can and cannot receive based on the sender, the color and shape of the envelope or the way the stamp was stuck on.
Read the terms of use of these providers carefully and react immediately to irregularities that are reported to you by people in your personal environment. ("Hey, I sent an email last week. Didn't you get it?")
If you hear something like this, be on high alert.
If your "mail provider" cannot help you satisfactorily with this problem, the only answer is: "Adios!!"
For a company that relies on an email address from such a provider, this is not only embarrassing, it is also tantamount to business suicide.
Imagine that an email provider decides whether to deliver an email with a lucrative order for the company or to reject it as supposed spam. Or the applicant who waits in vain for a job offer or a confirmation link to be sent to him.
In Europe, this is actually unthinkable!
It is to be hoped that supervisory and regulatory authorities will intervene and soon put a stop to these machinations.