What is the UID field in the tracker code, and how can I use it?
Both the web and email trackers have a UID value in their code.
This is an optional field, but you can use it to track unique visitors
and email viewings. You can set the UID value to anything you'd
like. Some common values might be the recipient's email address,
or just sequential, unique numbers. By giving each recipient their
own unique UID value, you can see both the total and unique accesses for
all your trackers. For example, if one user followed a link from
within their email 10 times, this would show up as 10 total accesses,
but only 1 unique access, since all 10 accesses had the same UID.