When Cambridge marketing software firm HubSpot Inc. launched in 2006, e-mail pitching was considered old-fashioned and spam-riddled. Consumers struggling with e-mail overload were often not receptive to more electronic clutter. HubSpot didn’t build its own e-mail marketing products. That changes on Tuesday, when HubSpot will at last offer tools to manage, create, and track e-mail marketing campaigns in its standard menu of services. It’s a mark of how much life the company thinks is left in the old Internet standby.