Edit: Thank you all for your answers and comments. As a result I have decided per your recommendations not to email the new HR manager, but I will mention this work experience if I am lucky enough for an interview. I've always wanted this position which is very rarely advertised, and have worked extremely hard to gain the experience necessary, so I really appreciate everyone's help in regards to this!
Three years ago I performed work experience for a large company based out of the USA. The HR manager at the time helped me organize this work experience and mentioned to me that 'she looks forward to seeing my application in the future'.
I have been building my experience ever since, and have just found out that the position I have always wanted has been advertised. However, I have just found out via a press release that a new HR manager has taken over her, as the old HR manager who helped me organize this work experience has since retired.
I am wanting to send a follow up email to the new HR manager mentioning my previous work experience organized by the old HR manager, but I would like to explain why I am sending the email to him.
I was thinking something along the lines of:
I wanted to send this email to you as I understand that Ms. XXXX has since retired, and you are the new HR manager. I have been watching for opportunities to arise at XXX since this work experience placement.........
I've also though of using the sentence 'and you have since taken over her position'. However both sentences including the part in bold/italics seems a bit rude. Is there any better way that this can be explained to the new HR manager on why the email is now going to him?
Thank you again for your assistance! Really appreciate it.