how to block sender with empty email address?

Hi laomashitu,

when dealing with the issue of blocking emails with blank sender addresses in Exchange 2016 Server, it's important to have a rounded approach to email security. Here is what you can do:

1. Use Connection Filtering:
- Think of this as creating a list of trusted and untrusted sources. Configure Exchange to block emails from known suspicious sources or IP addresses frequently associated with blank sender emails.

Configure the default connection filter policy | Microsoft Learn

2. Enable Recipient Filtering:
- This is like a gatekeeper checking if the mail is addressed to a valid recipient. By enabling this, you can prevent emails with blank or invalid recipient addresses from reaching your inbox.

Recipient filtering procedures on Edge Transport servers | Microsoft Learn

3. Consider Sender Reputation:
- Think of this as checking someone's reputation before allowing them into your home. Use sender reputation filtering if available in your anti-spam solution to assess the trustworthiness of the sender's IP address.

Sender reputation procedures | Microsoft Learn

4. Set Up Content Filtering:
- it is important to having a filter that screens out certain words or phrases. Create content filtering rules to catch spammy content even in emails with blank senders.

Content filtering procedures | Microsoft Learn

5. Keep Everything Updated:
- Keep your anti-spam solution up to date with the latest spam detection techniques and rules.