I'm facing problems with a few campaigns. The open rate is very low. Like below 0,01 percent. 5000 emails sent, 2 views. I'm trying to find the error but I can't. I'm using different purchased optin email lists from the US. And also different software and mail servers. There may be optin lists with 2% or 5% open rate, but 0,01% is very low. What's the reason?