For communication to be truly effective, it should be a two-way process. And for managers to be truly effective, they should know this. By ignoring your responses to his email, your manager is simultaneously wasting time, interfering with productivity, and generating dissatisfaction and stress.
If he is not satisfied with your communication for any reason, he should discuss his concerns with you, provide some coaching if necessary, and establish clearer guidelines regarding his expectations. His tendency to become upset with you underscores his ineffectiveness.
At the same time, it will be helpful for you to take a look at your “thorough” answers to his questions. Perhaps you have been writing more than the questions warrant, and that has been preventing your manager from carefully reading your responses. As in many aspects of communication, especially in the case of email, brevity is a virtue.
Finally, you should consider making a phone call or personal visit to clarify your answers to your manager. In fact, such communication is useful not only in clarifying your answers, but also in clarifying his questions in the first place.
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