How to track impressions in promo emails

If you wanted to track the impressions of promo emails created in Post Affiliate Pro, then into the body (message) of promo email you have to add the  following code (make sure you use HTML view):
<img src="URL_TO_PAP/scripts/imp.php?a_aid={$refid}&a_bid={$bannerid}" width="0px" height="0px">
Do not forget to replace "URL_TO_PAP" with the real URL address leading to your installation of Post Affiliate Pro (URL has to contain protocol 'https://' or 'https://').
This impression tracking code could be added automatically by variable {$impression_track}.
In the above mentioned sample impression tracking pixel we presume the affiliate URL parameters regarding "affiliate id/referral id" and "banner id" have not been changed in the merchant panel at Configuration > URL Parameter names.
NOTE: if the particular customer to whom the email is delivered uses an email client that does not support HTML output, then the impression tracking pixel won't be executed.