Finding lost alumni is a priority for many alumni departments, and understandably so. The more alumni that you identify, the greater your pool of prospective donors.
Traditionally, lost alumni are considered those whose contact information including mailing address, email, or telephone number are unknown. In general though, lost alumni may also be those who aren’t being contacted – either because the institution doesn’t have their updated contact information or because the students transferred out before graduating so their names aren’t in any alumni database at all.
Most alumni departments agree that good data makes alumni engagement more successful. Lost alumni are usually the result of bad and or misleading alumni data.
A client recently found the CFO for HP in her updated alumni data. This person had been in their database all along but because of stale data, she was still registered with her maiden name and had been considered a lost alumnus for years.
Without fresh data, many alumni records still have the names, addresses, emails, and phone numbers from the days when the person was still a student. We see this quite often. By this time, you may as well consider them lost.
In most institutions only graduates are considered alumni. However we have seen plenty of instances that prove the importance of looking at your non-graduated alumni. One of our favorite examples is from a client who found out that one of their non-graduates had become the CEO of Charles Schwab. There’s nothing to lose from finding these alumni, only potential to be gained.
Preventing the Problem
Take proactive measures before your alumni leave campus. Encourage your students to sign up on LinkedIn or other alumni networks so you can easily keep track of them once they have graduated. 
Make it fun!
There are a handful of stories where finding lost alumni has been converted into a game. Our favorite example, from a CASE review on Lost Alumni tactics, was called “The Great Alumni Hunt“. 
They channelled the game show spirit – prizes and all – to get groups consisting of one faculty or staff member, a student intern, and a community member to compete in weekly challenges that were aimed at finding lost alumni. And what better for motivation than a $2,500 scholarship for the intern of the winning team, and $500 for the runner ups. Apart from being a fun challenge, this also turned out to be truly rewarding to the alumni departments with over 1,000 lost alumni to add to their records. Get creative and make it fun, not only are you obtaining important data but you are encouraging some team spirit.
Don’t let stale data keep you from making important connections with your lost alumni. There is a wealth of data waiting to be discovered among your graduates that can lead to huge gains for your institution.
 Simple and creative ways to find lost Alumni, Hivebrite.com
 Loved, but Lost by Robin L. Flanigan, Case.org