Marissa Mayer, Chief Executive Officer of Yahoo speaks during a session at the World Economic Forum (WEF) in Davos January 25, 2014. REUTERS/Ruben Sprich Yahoo has patented a system that will "pre-deliver" emails before you send them, according to a new patent filing.

The document outlines a technology that monitors how people use email and watches for regular patterns.

If someone regularly forwards or sends the same email every day or after a certain action, then Yahoo will quietly send that email for them, but it will remain hidden. Then, when it's actually sent, it will show up.

And if you don't send your regular email, then Yahoo quietly deletes the hidden version after 24 hours.

Why does Yahoo care about pre-delivering email? Well, using this method it can send emails at times that suit it best — such as when the network isn't under heavy load. Yahoo can secretly pre-deliver messages during what it calls "off-peak" times, and then they show up when they're actually sent.

The patent was originally filed by Yahoo employee Varun Bhagwan in 2014, but it was granted to the company on Tuesday.

Here's a description from Yahoo's patent filing of a scenario in which pre-delivering an email would be useful:

"Bob receives an itinerary email from an airline or travel agent. For the purpose of non-limiting example, assume such an email is sent to Bob by JetBlue.RTM. after booking airline tickets for an upcoming trip. Bob typically forwards such types of emails (especially airline ticket itinerary emails) to Jill (his wife). As discussed in more detail below, this behavior or pattern is recognized by the disclosed systems and methods, and thereby triggers a rule. In this case, the rule associated with such pattern triggers the JetBlue.RTM. email being automatically pre-delivered or forwarded to Jill. As discussed herein, such pre-delivery involves the email being sent to Jill's inbox; however, the message is not displayed in her inbox. The message is hidden due to the display flag being set to "false" upon it being first sent. This pre-delivered email can be sent during times of low or "off-peak" network or system utilization to better manage bandwidth utilization in the email system and associated network(s).

Sometime in the future, Bob may act in his usual way and forward or send the itinerary to Jill. When Bob forwards/sends the travel itinerary email to Jill, this will not result in the email being re-sent but rather will trigger a transmission to trigger the display flag in the pre-delivered email to change to "true." In other words, when Bob finally "forwards" the email to Jill no further email is sent, but rather the previously pre-delivered (and hidden) email will be displayed (or appear) in Jill's inbox by virtue of receipt of the flag change message. The timestamp for such delivery will be associated with the time Bob actually sent/forwarded the email (not the pre-delivery time). However, embodiments can exist where the timestamp may be associated with the pre-delivery time."