If you have your gateway in SETTINGS > ROUTING > INCOMING GATEWAYS > SPAM set to "Pass Score to Smartermail" for your different Spam Levels (Not, Low, Med, High) then your other SM servers should be automatically reading this header and handling email these emails according to how your Server, Domains, and Users have configured their Spam Settings for each of those levels.

 

If you are not using Smartermail on your other servers, your SETTINGS > ROUTING > INCOMING GATEWAYS > SPAM on your gateway should be set with the actions you want taken for each Spam Level (Not, Low, Med, High), in which case the X-SmarterMail-SmartHostSpamWeight: header is essentially informational for troubleshooting.