In iOS 7 and later, there are two ways to block junk email from your iPhone or iPad's Mail app. The first method is to set up an email server rule with your email provider. The second method is simply to mark spam messages as junk email as you get them, which you can do on your iPhone's Mail app.
Using Mail Rules
If you're using your iCloud email address or forwarding your emails through iCloud email, you can set up a mail rule on the iCloud website. If your mail is coming through a provider such as , or , use the filters for that service to direct spam messages to your trash or junk folder.
Log in to your Apple iCloud account in any Web browser using your Apple ID email address and password. Click Mail, then the Gear icon and select Rules.
Click the first menu, below If a Message, and change it as needed. The default option, Is From, filters messages from specific email addresses or contact names. You can also filter emails with a specific word in the subject or any emails with a specific email address or contact name in the CC field.
Enter the email address or the name in your iPhone's Contacts that you want to block in the first text field. If you are blocking emails with a specific word in the subject line, enter that word here instead.
Click the Then menu and select Move to Trash to delete all of the spam emails. Otherwise, leave this option at its default Move to Folder setting.
Click Done to save the new rule. All emails passing through your iCloud email address will be filtered through the rules you specify in this page. To change or delete a rule, come back to the Rules screen and click the i icon beside the rule.
Moving Email to the Junk Folder
Open the Mail app on the iPhone and locate the email to mark as junk or spam. Drag the email's name to the left and tap the More icon.
Select the Move to Junk option from the menu that opens. If you change your mind, you can undo this action by opening the Junk folder in the Mail app, open the message, tap the Folders icon and move it back into the Inbox folder.