Microsoft Exchange allows you to restrict the IPs that are allowed to deliver email to it.  Because spammers might have cached the IP address of your mail server, it would be a good idea to only allow email from SpamHero IPs to force all email through our filter.

Before making changes to your Exchange server, login to the SpamHero control panel and go to Settings > Delivery mail host. Change the Mail host configuration to Mail host will only accept email from specified IPs or on a specific port (and leave the port blank or set it to 25):

Microsoft Exchange 2013, 2016 & 2019

Exchange 2013 uses a web based interface called Exchange Admin Center (EAC).  From the EAC, do the following:

1. Select "mail flow" -> receive connectors.
2. Select "Default Frontend [servername]" and click the edit icon (looks like a pencil).
3. On the "Default Frontend [servername]" select the "scoping" option and then select the default IP address range (0.0.0.0-255.255.255.255) and click the remove icon (looks like a minus symbol to the right of the edit icon).
4. Click on the add icon (looks like a plus symbol) to add the SpamHero IPs one at a time.
5. After all SpamHero IPs have been added, click on the save button.
6. Restart Exchange to activate your changes.

Microsoft Exchange 2007 & 2010

1. Open the Exchange Management Console.
2. Go to Server Configuration -> Hub Transport -> Default Receive Connector -> Properties -> Network tab.
3. You will see a section that says "Receive mail from remote servers that have these IP addresses". 
4. Remove the default rule for 0.0.0.0 to 255.255.255.255.
5. Add the SpamHero IPs one entry at a time.
6. Stop and restart the MSExchangeTransport service.

Microsoft Exchange 2003

To do this using the Exchange System Manager:

1. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. In Exchange System Manager, expand the following object:

        Servers -> [ Your_Exchange_Server_Name ] -> Protocols -> SMTP

3. Right-click the virtual SMTP server where you want to restrict inbound IPs, and then click Properties.
4. Click the Access tab, and then Connection...
5. Add the SpamHero IPs.
6. Enable the "Only the list below option" and add the SpamHero IPs.
7. Restart Exchange to activate your changes.