I sent out an invite thru Marketo and I am a little concerned the email went straight into their junk/spam folder. I did change the "From" & "Reply" to my email address.
Not for a specific individual but you can get a pretty decent idea of how the email is being treated by specific email providers if you use the Inbox Informant of the 250OK Deliverability Tools.
Thank you for your response. I am new to Marketo and is this 250OK Deliverability Tools available thru Marketo?
It's a third party product that you can acquire through Marketo directly at a discount to their usual cost.
I've used 250ok and you should keep in mind that it is based on their test accounts. So you run your campaign through their test leads before you send the real campaign out. It will give you a breakdown of what it sees in terms of Spam, Missing, etc...at the inbox level. This is directional only and you may have to test dozens of campaigns before you can say anything conclusively.
It is not so good at explaining all the reasons this might happen, although it does try.
Also take a look at benchmarks from 250ok and ReturnPath.