Yes, in addition to the Email field you can merge a custom field into the tracking link.
The custom field will not be passed to G-Lock Analytics. It will be passed to the browser only and will be used to identify the recipient on the server to access certain content.
No specific code to track email prints and forwards is required. The code you use to track email opens already includes the code for tracking prints and forwards.
G-Lock Analytics plans are limited by the number of subscribers in your list. A “subscriber” means a unique email address.
Tags help sort the campaigns out. If you enter a tag for your campaign, the tag is added before the campaign name in your account.