The reason given in the error messages is that your (?) IP address is associated with originating spam.

Thank you for the info. I kind of gathered that from the message. However, I still have the problem. And I do NOT engage in any kind of activity, that can be seen as suspicious - thereforeI have never had a similar problem.

Any solutions, please?

And I do NOT engage in any kind of activity, that can be seen as suspicious - thereforeI have never had a similar problem.

I had the same problem a few years ago. The problem was that there were spammers using the domain of my email address. You could contact your Email provider for advice but it isn't, I believe, a TB problem.