You seem to get more spam using SmarterMail than you did on your previous mail server

When migrating to the SmarterMail system from another host or mail service, you may notice what appears to be an increase in spam. What you are seeing are a lot of messages that other systems may have rejected, so they never made it to your inbox. SmarterMail works differently. It delivers all the email addressed to your domain and allows you determine how much spam you will see by fine tuning spam settings to meet your own preferences.

 By default SmarterMail is set up with a medium spam sensitivity. By going to: Settings > Spam Filtering you can select "Override spam filter actions," and choose how incoming spam is handled for a particular email address. After overriding the default settings, click the "Low", "Medium" or "High" windows to make changes. Click "Save" to implement the new settings.

 The above settings affect only the email account you are logged in to. To adjust default spam settings for all email addresses on the domain, go to: Domain Settings > Spam Filtering. Detailed information on domain-wide spam settings is beyond the scope of this article. Please see: Help for Users & Domain Administrators > Settings > Domain Settings > Spam Filtering.

For an overview of the default domain-wide spam settings, see this Knowledge Base article.