In Kyushu University, Information Infrastructure Initiative provides email service for students and staff members. Email services for students and staff members were started separately. For students, an email service was started as Unix accounts of "Computer System for Education" in 1995. On the other hand, an email service for staff members was started in 2009, and eventually the two mail services were merged into the current "Kyushu University Primary Mail Service" in 2014. The designs of these mail systems were affected by various operational issues and political decisions at their times. We think that running an in-house mail system is becoming less feasible due to the initial/operational cost, security issues, and our dwindling budget. For the current system, the planned 5-year lifetime ends in this fiscal year. Therefore, we are forced to migrate to a cloud-based mail service. In this presentation, we want to share our past experiences and future plans about our university email services.