Getting spam emails must be disturbing and dangerous if a user accidentally clicks on any link in the spam email. Then, it's recommended to block the spam sender, either its address or domain to prevent bad things happend on our email users. Here are the steps to block spam addresses or domains for the domain level.

1.  Log in to the SmarterMail web interface (http://mail.yourdomainname.com) as the domain administrator user.
2.  Click the Domain Settings from the top panel.
3.  On left side panel, click Content Filtering
4.  Click New button, on General section
      Name: rename the content filtering (e.g. Spam, Spam Block etc)
      Match Type: set as ANY condition must be met
      Enable wildcards: Disabled

5.  On Conditions section, click New Conditions to set content filtering rules
      Condition Type: From Address
      Field: From Specific Address
      Fill in the address to block on From specific addresses (one per line) column
      Click Save to update changes

6.  Repeat step 5 with Field: From Specific Domain
      Notes: for free email such as gmail.com, Hotmail.com, yahoo.com etc, should be block under Specific Address rules

7.  On Action section, click New Action
      Select Action: Delete Message
      Click Save to update changes
      Notes: Delete action will permanently remove the email on server level before reach recipient’s mailbox and it could not be retrieved

8.  Then, click Save on content filtering page for complete the setup