Capture Attention in Six Seconds
You have only six seconds to grab attention. If you can spark a fragment of interest, you might earn another twenty or thirty seconds.
What does this mean? You have about 13 words to hook them. If you hook them, you have maybe 30-40 words to deliver the most compelling stuff.
In order to compel a reader to pay attention to your message, you have to spend most of your time perfecting the first sentence. You need to prioritize the next couple of sentences.
With emails, the subject line becomes the most critical signaller.