Pop Ads has earnings potential as a pop-under ad network and it has safe ads but I wish it was more consistent in generating impressions. That being said, it can be one of the best pop-under ad networks out there.
If you are looking high payer network then try sisterads, poptm or popads. I recommend http://sisterads.com its cpm rate is higher than poptm and popads. Also you can talk on skype if facing any issues quick live support. If you have good traffic then you can become premium publisher and will be paid daily cpc rate more than $5 for US/CA/AU/UK. GO to sisterads and ignore others
Simply the best popunder adnetwork in the industry - try and check yourself!
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