"Robert has given this move a lot of thought and ultimately decided the time was right for him to realize his goal of leading a company," Sun President Jonathan Schwartz said in the memo.
Youngjohns wasat Sun in July 2002. He held the post until he was by Robert MacRitchie, and became executive vice president of strategic development and of Sun's financing unit.
Most recently, he led initiatives such as Sun'sservice, in which the company charges $1 per processor per hour to use a bank of Sun computers.
During his years leading Sun's sales, the Santa Clara, Calif.-based server and software company saw consistent declines in its quarterly revenue, which had boomed during the dot-com era. Revenue growth returned during his last quarter in the job, but itduring the most recent quarter.
Stuart Wells, who joined Sun in 1988, will take Youngjohns' post. Wells will report to Schwartz, Sun said in a statement Thursday.