Kansas man has been sentenced to federal prison after AOL’s automatic detection system caught him emailing child pornography.

Fifty-six-year-old Walter Ackerman of Lebanon was sentenced Monday to 14 years and two months in prison after pleading guilty to distributing and possessing child pornography.

Prosecutors say Ackerman possessed more than 750 sexually explicit images of children. AOL Inc. sent information to the National Center for Missing and Exploited Children, who alerted authorities.

Ackerman’s attorney argues the email evidence was obtained through cyber “snooping” in an illegal search and seizure. A federal judge ruled AOL and the center didn’t violate the Fourth Amendment.