With the current laws restricting junk email messages and the spam-preventive tools available in most email apps today, there's no reason to manually delete every unwanted message you may get. In fact, most email providers like Gmail, Yahoo and Microsoft have built-in filters that are probably removing a lot of your spam messages before you even see them.
Unsubscribe From Email Lists
By law, commercial email originating from the United States — and many other countries — must include a way for subscribers to opt out from future emails. If you subscribed to a newsletter, or asked to get updates from a website, you can almost always opt out of those messages. At the bottom of the last email message you received from the unwanted source, you should see a link giving you the ability to Unsubscribe or Manage Your Subscriptions. Clicking this link should stop future emails, although it may take a day or two for your cancellation to be processed.
Your email provider may have additional options for dealing with subscriptions. For example, Gmail adds an additional Unsubscribe link at the top of each message to make it easier to find.
Flag Emails as Spam
If anyone ever sends you an email that you didn't ask for, you can flag it as spam. The process is essentially the same for every email service and email app, although the positions of the buttons can vary.
If you're using the Outlook 2013 desktop app, right-click the email that you don't want, select Junk, then Block Sender. Alternatively, click the Junk icon located under the Home tab and select Block Sender. Note that the Junk button also has options to ensure emails from a particular sender or Web domain never get sent to the Junk folder by mistake.
If you use Hotmail, Live or any other Microsoft email service on Outlook.com, select the email and then click the Junk icon at the top of the page. Select Junk to put future emails from that sender in the Junk folder. If you suspect that the email is a phishing scam — in which hackers mimic legitimate websites in order to secure user passwords — mark it as a Phishing Scam instead. Microsoft uses this information to prevent the same scam emails from reaching other people.
Select a message in Gmail and click the Report Spam icon, which is marked with an exclamation point. The message and all future messages from that email address are sent directly to your Spam folder.
Select a message in Yahoo Mail. Click the More icon and select Report Spam. Note that Yahoo has a Report Phishing Scam like Outlook.com. You can also Report a Hacked Account if you suspect that someone's computer has been hacked or has a virus, resulting in spam messages being sent to you.