Google Analytics (GA) UTM tracking code generator https://support.google.com/analytics/answer/1033867?hl=en
Example below uses utm_content=Link1 to enable reporting separately on each link in the newsletter to see what customers are most likely to click on.
Example:
www.hotel.com.au/page1.aspx?utm_source=eNews&utm_medium=Email&utm_term=13Nov&utm_content=Link1&utm_campaign=eNews