The specific action for engaging an e-mail depends on the type of e-mail. At this point, remember, spam and personal e-mail are already gone from the inbox. The three remaining types of e-mail are newsletters, FYIs, and tasks.
Newsletters: Read (or scan) newsletters quickly, depending on how much time is available, then delete. If you have very little time and lots of other e-mails to engage, then quickly scan the headlines and delete the newsletter. If you have more time, feel free to read more of the newsletter. But whatever you do, do not file the newsletter with the intent on reading it later. When the next issue arrives there will be two issues waiting for attention. If you file the newsletter in a folder, archive it immediately.
By the way, this assumes that you already prune your newsletter “diet” to minimize any unnecessary subscribed e-mails. If you currently receive newsletters you never read, you should unsubscribe from them. It will save you more time in the long run.
FYIs: These are non-actionable pieces of information: for example, an answer to a question, or a notification of an event. An FYI might also be a BCC of your own outgoing message to someone else. Whatever it is, read the FYI, file and archive it if necessary, then delete it. Note that filing may involve scheduling an activity, like a meeting or appointment, on the calendar. In any case, the FYI must be deleted afterward.
Tasks (To-dos): Use the “two-minute rule” for tasks: if it takes two minutes or less to complete, do it immediately (even if it means physically getting up from your chair), and then delete the e-mail. If the task would require more than two minutes of your time, add it to your task list, then delete it.
Note that you must delete each e-mail after you engage it. You might file or save an e-mail elsewhere before deleting, but no e-mail may remain in the inbox. Remember: the inbox is only for accepting incoming e-mail, not for storing it.
E-mails, no matter what kind or how important, are only allowed to stay temporarily in the inbox. You will save time by engaging each e-mail as soon as you read it.
