Conversion tracking for email campaign clicks is done using link tagging with Google Analytics (UTM) tags.
Links in email messages are auto-tagged by default with Google Analytics "UTM tags".
To enable link tagging for your account, check the "Enable Google Analytics link tagging by default" checkbox on the Settings page. This is ON for all new accounts.
When this setting is enabled, every link in every email campaign is auto-tagged with the following tags:
utm_medium = email
this cannot be changed
utm_campaign = [name of email campaign]
automatically populated with the name of your email
utm_source = [list of recipients]
automatically populated with the name of your recipient list
utm_keyword = [email subject line]
automatically populated with the subject line of your email
utm_content = [blank]
not populated automatically
If your message is called "Winter Promo" and you're sending it to "Newsletter subscribers" then links will look like this:
http://www.website.com/?utm_medium=email&utm_campaign=Winter Promo&utm_source=Newsletter subscribers
You can override the default values in the sidebar of the message editor.