The receiver will not correctly get your message. Body language is a major portion of any message we send. If we are happy and have a cross look on our face no one will ever know exactly what we mean. Present your message in more than one format. If someone is not understanding your message, think of a new way to present the information.
People are either visual, auditory or kinesthetic communicators.
They will give you major clues with the words they use. You will reach a potential client faster if you use the words they mentally tune into most comfortably. Ask for feedback. Double check all communication you send. Ask the listener to repeat your message in their own words.