Happy retirement @dinkiedoo. I understand how you feel. I left a place of work after nearly 20 years, and did not receive an e-mail wishing me luck, a card or even a snatched 'goodbye' from another colleague.
Like others have said, the most likely reason was that I had been off sick for a few weeks, and probably no-one became aware that I had left until it was too embarrassing for them to contact me, or because I had no access to work e-mails, and they had no access to my personal contact details.
It did feel a little unfair. Yet, the situation also made me realise how dispensable I was, and, because I am not quite old enough to retire (nearly there!), I learnt never to think of work as anything more than a way to make some money. Sometimes it is a pleasant and rewarding way of making money; other times it is a drudge.
Retirement may give you opportunities to make friends or to do things just because you enjoy them.
Look after yourself, and have a long and truly happy retirement.