At one of the companies that I worked at, one of the high-level architects had the same message. His message was simpler, it was something along the lines of:

At one of the companies that I worked at, one of the high-level architects had the same message. His message was simpler, it was something along the lines of: "I'm on vacation and will be deleting all my accumulated emails when I get back. If it's something important, please resend me the email after <date-of-return>." Personally I think this is fair because if it's important, the onus should be on the sender to make sure that the receiver reads it. Chances are 99% of his emails were just cc'es anyway, but if it's something that really needs a decision, then the sender should resend it.