Kelly,
Good question. Your Marketo emails and landing pages will have different tracking links. Depending on whether you've set up CNAMEs for one or both, they should be something like "info.company.com" or "get.company.com."
What this means is that the referral traffic from emails and landing pages should be categorized separately in your Google Analytics instance. So email referrals should be strictly from those who have clicked on a link in an email that went directly to your website from a sent or forwarded email.
If the user went to a Marketo landing page, then clicked a link to go to your main site, they will be tracked as referral traffic from your landing page, and not your email.
Hope that helps.