To block spam emails in Outlook, add an email sender to the Block Sender List by clicking Block Sender in the Junk drop-down menu at the top. Alternatively, create rules in Outlook to identify spam emails and automatically flag and move them to the Junk Email folder.
In Yahoo Mail, mark and block spam emails by clicking the Spam button. This moves the emails to the Spam folder and reports the senders to Yahoo. To block spam emails in the Web version of Gmail, select the emails and click the button that is shaped like an exclamation mark. To block spam on an Android mobile device, open the spam email and tap the menu that looks like three vertical dots at the top-right, and tap Report Spam.