In my opinion sending an introductory mail is certainly not the crime here. No doubt there seems lots of enthusiasm and energy in his mail but being a Sr. HR Executive his mail lacks professional touch and seems that of a College going guy. He holds a position which should show up some maturity than being fun and freak loving kind. This is where the importance of Summer training and industrial training one needs to understand and learn.
There is always a protocol to be maintained. Therefore, before sending out the mail it is important to understand whom it is to be addressed to and sent to and accordingly the content be designed. This kind of mail is certainly good among friends and peers but not to MD and other Sr. Management persons.
May be it was also too early for him to open up this way. Rather, he should have first tried to understand the culture of the organisation and there after by creating a good rapport with in the Company could have initiated for a culture change gradually and step wise if at all he felt the need in such a short period.
To my understanding and as also known to me thru some of my colleagues and friends in TATA group Companies, it is highly professional but a Culture Value based Company. Probably that is the reason the MD should have considered this kind of introductory mail to cause a dent in the existing culture of the Company.
Indeed, termination of the candidate is too disproportionate and harsh an action w.r.t the mail and not the right approach on MD's part. Even warning at this stage and for this reason is not appropriate.
Had I been the MD and not liked this kind of a mail, I would have called the HR Head and asked him to first praise for his enthusiasm and that we expect the same from him in his professional functioning too. Then introduce him to the existing Company culture, values and the protocols and Counsel and guide the guy in a fashion that he doesn't loose his enthusiasm and also respects the Values of the Company.
Members may differ with my opinion.
I offer all my best wishes and a good luck to him for a better job.
Parwez