Recently, I have been getting error messages when I'm responding to authors who send me a reprint request. The latest message is I cannot send messages to anyone not following me. Why is that? I don't follow the author I requested the paper from.

I feel it is a professional courtesy of a requestor to show appreciation for authors sharing their work. I can no longer seem able to do that and I'm not comfortable with that situation.

Am I doing something suddenly wrong? (I have not changed any account settings).

Can I reverse this?

Thanks in advance.