200
The customer has his email account configured on both the iPhone and his computer. Not all of his messages appear on the computer or the iPhone. When he uses his computer, new messages appear there, but when he uses the iPhone, the messages he reads on his computer do not appear, and vice versa. These could be the root causes of this issue.
What is the customer uses a POP account for his email, which removes messages from the server when he retrieves them, no matter which device he views them on. In doing this, the iPhone and the computer show only the messages that particular device retrieved from the server. To correct this, the customer needs to edit his account on the server so that the server doesn’t delete the messages after download.