Written communication has become much more common since the dawn of email. It is also the form of communication where you lose all non-verbal communication. Furthermore, you also have to consider that most people do not like to read long text and that there is no direct feedback when you use this form of communication.
When you use email (or similar forms of written communication) for communication with a user, you can often not analyze a problem completely based on the first message you receive. In many cases you will have to follow these steps:
You receive the first message from the user stating a rough description of the problem.
You analyze and find a few possible solutions and you determine what information is needed to find the source of the problem.
You send a first reply with the most likely solution and a clear list of questions that you will need the user to answer if the problem is not solved with the solution provided.
You receive feedback from the user that the solution provided did not work and answers to the questions you provided. With this information you are able to identify the root cause and provide the right solution.
You propose the final solution and ask the user to give you detailed feedback if your solution is not the right solution and you inform them that you will consider the ticket resolved if there is no response within a certain amount of time.
Sometimes the receiving feedback and proposing solutions happens a few more times before the true solution is found. Please note that because of the delay in this type of communication, it will often take longer to resolve an incident. To limit the time needed to solve issues through this medium this example of actions shows that you have to assume the most likely cause of the problem and provide the solution that will be most likely to work in the user's situation and sollicit feedback at the same time. Sometimes it may also be prudent to ask for a time and number to contact the user at a time that they have time to look at the incident together preventing long email threads and solving the incident faster in most cases.