First off this is not my job - I am being asked to help, so I am sorry on incorrect terminology.
I want to track all email traffic to our website. I don't care where it came from, just if it is from email. We send our email out through Convio and Slate - their referring URLs are //comm. and mx.technolutions.net. I would think it would be easy just to say if referral is ... classify as EMAIL, but it is not as they are being marked as Typed/Bookmarked. I read this article that seems like it might work, but would like to track all links (in case a source code is missed). Is there away to do this or to say if from any email client it = EMAIL?
Example: We send email out via Convio > person opens the email and clicks on the link (http://comm.com/?ID123) > that gets generated to (www.oursite.com/link)
Let me know if you need more info or clarification.
The only way to effectively track traffic coming from an email is to add a campaign code (a url param with a value) to all the links in the email that point to your site, and then look for that url parameter as the basis.
Most people just populate an eVar with the value, but the article you linked to shows a good trick for helping filter/segment for it in native referrer reports. But point is, only effective way to track traffic from emails is to append something to the links in the emails and look for it.
The reason is that it doesn't matter how you send the email out (whether you use Convio and Slate, or make your own code, or just manually send emails out yourself through gmail).. visitors receive and read the emails from within their own email client. This might be via a web interface like going to gmail.com but most people use some local client on their computer (e.g. outlook or some mobile "mail" app on their phone) and these things don't have referring domains.
And even if a visitor were to read their email in a web interface, most web interface email clients do many things to mask themselves, or it also may show up as their email server, not public server. But usually not at all, even then.
So, that is why currently the best practice is to add a url parameter to the links in the email, so you can look for that. Also, most people use different campaign codes. Sometimes they will have a single campaign code to be used for all links in the email. Sometimes they will create a different code for each link. It basically boils down to how granular you want the data to be, how much insight you want into how the visitor got from your email to your site.
It sounds like you would be content with just doing something like source=email on all links in all your emails. I recommend you be a little more granular than that, as I'm willing to put money on it that you or some other stakeholder will almost certainly want to know things like which email drove more traffic, and maybe even which link(s) in the email.
And if it is a matter of your vendor not being able to put campaign codes on email links.. then I recommend you find another vendor, as this is a very important and common thing companies require of email distribution vendors.