Reject Messages with Empty MAIL FROM

1. For version 5 of AXIGEN Mail Server
In order to reject messages with empty MAIL FROM header you need to add the following acceptance rule. From the Webadmin interface go to Security & Filtering menu, Acceptance & Routing context, Advanced Settings tab and click Add Acceptance/Routing Rule.

You are now in the New Acceptance/Routing Rule wizard. Follow the steps below:

• In the Rule name field write the desired name for this rule
• Click Enable this acceptance/routing rule check-box
• Choose Email under Sender from the Conditions list
• Click Add Condition
• Fill in the field for Sender email  is with <>
• Choose Action under SMTP from the Actions list
• Click Add Action
• Choose Reject from the SMTP action list
• Write an explanation for the action in the Explanation field (e.g. due to empty MAIL FROM)
• Click Save Configuration to save the rule

2. For older versions of AXIGEN Mail Server.
In order to reject messages with empty MAIL FROM header you need to edit the SMTP Policy file and add the following code:

event onEhlo{
if(is(mailFrom, "<>")){
    set(smtpAction, "reject");
    set(smtpExplanation, "Rejected due to empty MAIL FROM");
  }
}

NOTE:
NDR notification messages from remote servers may also be sent with an empty MAIL FROM header (MAIL FROM: <>).