This warning is a general connection error, and it can be caused by minor connectivity issues between the application and your mail server. It can occur when the server is not responding or if the number of requests is higher than usual and the server is unable to respond while the request is valid.

Don't worry though – eM Client should be able to automatically reconnect if the connection error is thrown unless there's a real problem on the server.

You can find more details on what causes this connection issue in the third tab called Log in Menu > Operations. If you need help analyzing the problem, get in touch with our support.