When a creative mails in a portfolio to our agency, it gets routed to me. Even when it is addressed to someone else, it will make it's way to my desk. A creative manager is the person who filters the candidates before anyone else sees them. So anything even remotely creative-related comes my way.
The other day a candidate mailed me a portfolio packet. A day later another copy of that same packet was left on my desk by the HR Director who was so kindly forwarding me the creative's work. Couple days later another copy of that same packet was left on my desk by a creative director who was so kindly forwarding me the creative's work. Kid you not, a day after that, another copy was left on my desk by another creative director who was so kindly forwarding me the creative's work.
Ugh. You do not need to mail the same agency 4 or 5 times over. I know you are trying to hit as many targets to up your chances of being noticed, but I'm not so certain this is a good strategy. Also, the amount of paper and postage it is taking to mail so many pieces must be time and cost consuming (and don't even get me started on the paper waste).
The ECD is not opening mail unless it is really important. His assistant is weeding through it and sorting out the things that are essential for his eyes and turning the candidate-related stuff over to the creative manager.
The HR Director is sorting through their mail and turning the creative candidate-related stuff over to the creative manager.
The Creative Directors are most likely opening their own mail. At bigger agencies, they may have assistants doing it. Sending one to them might prove helpful. But ultimately they'll turn the candidate-related stuff to the creative manager to follow up on.
Be selective and targeted with to whom you send your information. Your follow up with the correct person (the creative manager) is what's really important.