I'm looking for the definition of terms you use in traffic sources in Explorer: what's the difference between "email marketing", "webmails, and "portal sites"?

AT Internet natively distinguishes 2 sources types:

• organic sources (by default, without tracking variable)
• marketing sources (tracking to implement)

Email marketing corresponds to e-mailings campaigns which generate traffic on the website. 

Webmails represent traffic coming from online messaging service, based on the JavaScript referrer.

As the main difference, we note that the email marketing is a marketing traffic source and webmails is an organic traffic source. 

We define portal sites as an option which has to be activated (it's not a standard source). It gives access to all sites of the contract that generated traffic on the analysed site.