Note, the problem really only exists if you print a URL in the email, and the hyperlink in the HTML is different. For example if you put "visit <link>my website</link>" instead of <link>www.mywebsite.com</link> and put the tracking URL on the link as you would normally the problem goes away.
I think you just have to be creative on this.
The information was only anecdotal. If you search SpamAssassin's list of spam flags it might reveal more info.
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