Statistics and Tracking
The Statistics component tracks actions of subscribers on emails you send. The statistics module tracks two main events: the opening of an email and the clicks on links of an email.
While a click can always be tracked, the opening of an email can be tracked only if the user enable the download of images on his email client. This is a common problem every mail marketing system has.
Tracking is enabled by default on every newsletter, but you can choose to disable it newsletter by newsletter. Technically there is no serious reasons to disable tracking, and as you can see on email you receive from mail marketing systems, links are always rewritten.
The statistics module is active on the standard version of Newsletter plugin (since version 3.0) and the Professional Extensions will extend this module to show charts and tabled data.
Where can I access the statistic data?
On Newsletter panels, where there is a list of emails there is a link for each email that opens the statistics page. The statistics page of an email is the same independently of the nature of that email: it can be a newsletter manually composed and sent, or an automatically generated email, like the ones of the Feed by Mail module.
Statistics on standard version shows some aggregated data, like the number of email opened. Newsletter Extensions (or Nerwsletter Pro) extend this panel to show more detailed data and some charts.
Tracking URL and spam filters
Since version 3.7.1.
Since February 2015 a famous spam filter, Spam Assassin, added to it’s spam detection rules a new check looking for link containing the “wp-content/plugins” path. Probably this was done because hacked blogs can have injected bad files inside the “plugins” folder. A similar check is made with the “themes” folder.
Newsletter has the link click tracker on that path, so there is a serious risk to be blocked by Spam Assassin. Of course Newsletter link is totally legit and secure.
To deal with this issue you can change how the tracking URL is generated and, other than the standard mode, you can choose the “Blog Home URL with parameters”. The blog home should never be blocked by spam filters (of course if your domain is not in a black list!).
The possible problem with this tracking URL mode is the interference with caching, security or SEO plugins: some of them modify or block URLs with parameters. A little check with a test newsletter and few click on tracked links should suffice to verify possible incompatibilities.