Communicating via email is significantly faster compared to logging in and typing responses in the ServiceNow portal. However, when a user responds to an email, the email response is not posted to the case portal. This means there is no clear documentation for issues. If a user wants to review old issues, there will be no record of responses made by email.
Totally agree - I thought I had posted required information in a CS post, but I had submitted the information via email, so the critical info is not all in the posted history.