Canons of e-mail

Adam Smith set the following "Canons of Taxation" to determine if a tax was a 'good' tax... The cost of collection must be low relative to the yield The timing and amount to be paid must be certain to the payer The means and timing of payment must be convenient to the payer Taxes should be levied according to ability to pay Here are my "Canons of e-mail"...

• The time necessary to read the e-mail must be low
  
• The timing and action to be taken must be certain to the reader
  
• The timing of the e-mail (and any related request for action) must take into account the reader might actually have a life, job, and such... and they are not glued to their inbox in anticipation of the next missive
  
• E-mails should be sent according to ability of the reader to absorb and act