Campus based College Ministers should be fired if they don't....work with alumni. That's probably too strong of a statement, but it conveys how important I think this is.
Why is it that important that you work with alums?
First, you still have spiritual influence in their lives. You should not walk away from that. Through the years one of my frustrations has been Youth Ministers who did not seem to feel any responsibility in a youth's life after they graduated. Some could not even tell me where their youth group members were going to college. Yet, some times as College Ministers we don't realize how God can continue to use us in the lives of our alums at key times. They may need to talk to you about their marriage. Some may need to call when there is a crisis in their church. You get the idea.
Second, alums can be a powerful voice for the value of Collegiate Ministry in their local church and within their denomination. Today in the time of cuts due to finances, former students who have been active in your ministry can speak to how God uses College Ministry. Do your alums know the value and power of their speaking up? Keep them informed about recent developments related to your ministry and College Ministry in general.
Third, alums can be a consistent source of financial support of your ministry. As funding is cut to many ministries, your alums can make a difference. Through the years we have asked our former students to consider giving $25 a year. Many would say through the years, "I would give you some money, but I can't give enough to help". Lots of $25 gifts add up....and some will give more than $25 a year.
But, there is a difference in being involved with your alums and just asking them for money. Alum newsletters need to be mostly news about alums...not just a letter asking for money. God used you in their life when in school and he still can. It's never too late to start working with alums!