Snoozing means archiving an email temporarily, and having it automatically reappear in the Gmail Inbox at some specified time in the future. With Apps Script you can extend Gmail to add this functionality.

By the way – if you don’t want to code your own solution, DNDEmail.com will do this automatically for you, for free.

Even if you don’t know how to write a script, it’s pretty simple. Be sure to login to Google Docs with your Gmail email address. Go to Google Docs and create a new spreadsheet, then choose “Script Editor” from the “Tools” menu. Paste in the following code:

var MARK_UNREAD = false;
var ADD_UNSNOOZED_LABEL = false;

function getLabelName(i) {
  return "Snooze/Snooze " + i + " days";
}

function setup() {
  // Create the labels we’ll need for snoozing
  GmailApp.createLabel("Snooze");
  for (var i = 1; i <= 7; ++i) {
    GmailApp.createLabel(getLabelName(i));
  }
  if (ADD_UNSNOOZED_LABEL) {
    GmailApp.createLabel("Unsnoozed");
  }
}

function moveSnoozes() {
  var oldLabel, newLabel, page;
  for (var i = 1; i <= 7; ++i) {
    newLabel = oldLabel;
    oldLabel = GmailApp.getUserLabelByName(getLabelName(i));
    page = null;
    // Get threads in "pages" of 100 at a time
    while(!page || page.length == 100) {
      page = oldLabel.getThreads(0, 100);
      if (page.length > 0) {
        if (newLabel) {
          // Move the threads into "today’s" label
          newLabel.addToThreads(page);
        } else {
          // Unless it’s time to unsnooze it
          GmailApp.moveThreadsToInbox(page);
          if (MARK_UNREAD) {
            GmailApp.markThreadsUnread(page);
          }
          if (ADD_UNSNOOZED_LABEL) {
            GmailApp.getUserLabelByName("Unsnoozed")
              .addToThreads(page);
          }          
        }     
        // Move the threads out of "yesterday’s" label
        oldLabel.removeFromThreads(page);
      }  
    }
  }
}

Then click the “Save” button and give it a name.

In the dropdown labeled “Select a function to run,” choose “setup” and click the blue run arrow to the left of it. This will ask you to authorize the script, and will create the necessary labels in your Gmail. Then go to the “Triggers” menu and choose “current script’s triggers.” Click the link to set up a new trigger, choosing the “moveSnoozes” function, a “time-driven” event, “day timer,” and then “midnight to 1am.” Click save and you’re done.

To “snooze” a thread, use Gmail’s “Move To” button to move the thread into the “Snooze for X days” label and archive it. Every night, threads will move up through one day of the queue, and at the appointed number of days they will reappear in your inbox, unarchived.