We used a tool called Freshdesk in which sending an email to a particular email id creates a support ticket. Also you can reply from it's dashboard. We had b2b customers who used to send a lot of queries everyday. This tool helped in distributing queries among the team. Earlier it was only one person mostly who was handling all queries, thus was overwhelmed. Also it has auto rules which can be used to set priority to the tickets. Very useful tool when you have a sizeable number of customers. It helps in providing better customer service also as very few tickets go unanswered .