Case: an email came from a supplier which was received yesterday and was removed by our system administrator as it contained virus. I can only know that he is one of our suppliers by his email address. I need to inform the supplier that his email was blocked by our system administrator and thus I can't see the message body from his email.
Dear Sir/ Madam,
Your email was received on 15 March 2015. It is noted your email contained viruses and cannot be opened. Please remove the virus and resend the email to us. If you need further assistance, please contact our supporting team at xxx-xxx-xxx.
I would think that "Your email was received on..." would be more polite than using "I" unless you are speaking to the supplier person-to-person with colloquial language. If you are speaking to the supplier person-to-person but with formal language, use what I put in.
Actually, if you are speaking person-to-person, either don't use "I" or don't use "us". In the first sentence in your draft, you stated "I" meaning yourself. In your third sentence in your draft, you wrote "us" meaning your company or business as a whole. That would be contradictory so either use "I" and "me" or "We" and "us". Then you put in your regards as Don, implying that you mean you are speaking to the supplier by yourself.
What about a "Please do not reply?" just in case?
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