Reading the email in the linked post, I don't see any "personal note" in there. Other than the first name which, as redguava points out, is easily obtainable. It looks personalized, sure. But there's nothing telling me it isn't sent by a cron job.
In the early days of the internet, I may have fallen for something like that... only to realise my reply went to a ticket support system or a fake 'from' address. Nowadays, I'm cynical about welcome messages and just delete them.