Often, even in email relationships, an Abuser will set you a task. Something time consuming and from which you get absolutely no benefit whatsoever.
The ‘task’ means nothing to him, getting you to perform it means he Controls.
So he writes a long missive asking you to do this and that and next.
Here he is, trying to get you to do, think, believe something. And what do you do? Argue? Complain? Act Annoyed? To do any of these things proves they ‘got’ to you.
To ignore is your victory.