First-in, first-out distribution
Do your agents spend a lot of time cherry picking emails? We run first-in, first-out distribution for all kinds of conversations, email included. We've found that in the long term, this benefits your customers as each agent improves their skill and also don't waste time going through email inboxes. If an agent is unable to answer an email they can simply transfer it to a colleague. Finally, agents should only be part of queues that receive emails in their area of expertise.