Connecting your email marketing with other channels is the ultimate way to track engagement and the assists that lead to the eventual conversion.
If customers don’t buy right away or don’t buy online, are you able to track the fact that they initially came in from your email marketing but only later purchased after visiting from other channels, including off-line?
Keep notes about your customers in CRM system like Salesforce, or better yet, integrate your website, email campaigns, Salesforce, and HubSpot. That way you can follow visitors on their journey from your email link to your blog, and then off to your social channels and back again, perhaps through a direct type-in. Only then will you have a clear ROI metric.
Photo credit: CeBIT Australia / Foter / Creative Commons Attribution 2.0 Generic (CC BY 2.0)