"Time to say Good Bye" mail

when a professional leaves his present organisation for next company, he drafts a thanking mail with lots of manufactured (may be real) emotional and nostalgic feelings he had experienced while working in various projects with various teams and he sends to all members of his present as well as past projects. what does this courtesy mail leave an impact on employees who get this mail? do we get emotional as this guy is leaving us ? does HR team see an infectious virus being sent by a out-going employee in the form of a thanking mail ? ok. let me tell you...how an employee reacts after reading a 'Good Bye' mail as this mail directly motivates them also to say 'Good Bye'...if that out-going employee is his friend then he will inquire about the offer he got and he will request him to refer his resume when he joins there...otherwise he will also start looking for a better opportunity in term of salary because someone having same experience as his own are getting better package in the market then why he should be left doing work at lower salary in his present company. many times this mail left many employees in bad taste as well as demotivated as they missed to grab that more-paying job. so what happens...one 'Good Bye' mail motivates next three or five 'Good Bye' mails directly or indirectly. from organisational perspective, this practice is no way doing any good.