How to Block a Sender in Mac Mail. Mac Mail is an excellent program to send, receive and manage email, but with any email provider comes unwanted mail. Fortunately, Apple, the maker of Mac Mail, provides users the ability to block unwanted senders through Mac Mail. Use this feature to block mail from a single source or from any number of sources as needed to receive only the mail you really want to read.
Log in and open up Mac Mail. Click on the word "Mail" at the top left hand corner of the screen.
Click for the word "Preferences" at the top right hand corner of the page.
Search for the rules tab and click on it. Then find "Add Rule" and select it. Choose "From Contains" as the criteria.
Block the unwanted sender's email address. Type in the sender's complete email address, including the "@" symbol and the email provider. Do not put a period at the end of the email address.
Choose "Delete message" in the actions section. Label the rule in the "Descriptions" section by typing it in. Each rule needs a description in the event that it has to be referred to again.
Close the dialog box by clicking "OK." Repeat these steps to block additional senders as needed.
Apple also has a feature to filter and block spam emails automatically. Mac Mail storage space is valuable, so use this feature to combat spam from unknown sources.