Please be careful creating a blacklist or you may unintentionally block legitimate email.

You can create a domain-specific "blacklist" to block email from specific sources. It can be used for things like blocking email from someone who is harassing you by email. Or you might want to block recruiters who are trying to steal your employees. Basically, it's to be used for blocking email that you receive that can't be considered Unsolicited Bulk Email (UBE) and blocked globally by us.

Important: Please do not use this to block spam (UBE) that is making it past our filters. That's our job. Instead, send a plain text message including the complete headers and message source of the spam to us. That will allow us to investigate why the email made it past our filters and find the best way to prevent it from happening again, not only you but for the rest of our customers.

Note: When you blacklist an IP address, you blacklist an entire mail system, and you will block all email from that organization. While this is probably acceptable with small organizations, be sure not to blacklist the IP address of a large ISP's mail system that your clients or contacts may be using. (See step # 2 below for assistance.)

Blacklisting by IP Address

1. Determine the IP address of the organization's mail server to be blacklisted.

   This can be done by examining the headers of e-mail messages from the organization.

2. Go to www.dnsstuff.com and enter the IP address into the "IPWHOIS Lookup" box. This will tell you what country this IP address is assigned to, and sometimes the name of the company that owns the IP address. This will help you decide if you should blacklist the IP address.

   You probably don’t want to blacklist major email systems such as Yahoo, Hotmail, AOL, etc., since you would be blocking all email from those services. These services are used by many legitimate home and business users.

3. Click on "Edit" next to "Domain Blacklist".
4. Click on the "Create new entry" link.
5. Under "Blacklist Options", select "Blacklist by: IP Address" in the list box.
6. Enter the IP address of the mail server (in dotted decimal notation, ie. 123.123.123.123) in the "IP Address" text box under "Blacklist Arguments".

You can also specify "Comments" that will help you to remember why this entry was created.

7. Click on the "Create" button to create the entry.

Blacklisting by Email Address

1. Determine the sender's email address to be blacklisted.
2. Click on "Edit" next to "Domain Blacklist".
3. Click on the "Create new entry" link.
4. Under "Blacklist Options", select "Blacklist by: E-mail Address" in the list box.
5. Enter the email address in the "E-mail Address" text box under "Blacklist Arguments".

Optionally, you can block all email addresses at a specific domain by specifying just the domain preceded by the at (@) symbol in the "E-mail Address" text box. For example, to block all email from users at annoying.com, you would enter:

@annoying.com

You can also specify "Comments" that will help you remember why this entry was created.

6. Click on the "Create" button to create the entry.

To change the Domain Blacklist action taken when the message is filtered:

1. Click on "Edit" next to "Domain Blacklist".
2. Scroll to the bottom of the page and select the action you would like to take on email caught with this filter.
3. Click on "Set" to save the changes.