To send an email to a Japanese colleague with whom you may wish to collaborate on a potential business deal, you should begin by addressing the individual warmly and openly by their first name. This immediately closes the cultural gap. Then, use the last name followed by the term 'sama' or 'Formal version of Mr.' to address your email. Use clear text with utmost formality and avoid making assumptions for context. The Japanese are accustomed to informal communication from other countries, but it is still important to adapt to their customs.