You're going down a long rabbit hole with email servers and cold emailing. I've been optimizing my email server for over a year to scale successfully because there are not many resources on it. Yes, there are tutorials on building a server. But when trying to scale you run into scaling problems that you can't get from any tutorials online. My server is a mautic + mailwizz with postal as the sender. 2 VPS servers. Mautic is used for cold email marketing and once the campaign is sent. I send active subscribers to mailwizz for additional emails in the future. BUT YOU CANT SPAM. If you have a good-sized email list. Keep the campaigns to 2 months long. So your first email sent, he/she doesn't receive another email for 2 months. The lastest email campaign for me was a total of 27k emails, scaled up to 1000 a day, the beginning is slow. 50% open rate. Your leads have to be rock solid to not end up in spam. If you're getting a low open rate that's an easy sign for spam. I landed in inbox the whole campaign, so it was a success. But the leads are the hardest part to acquire for scaling. Start research cause I still think cold email marketing is a viable strategy. Email marketing is perfect for establishing connections and building up relationships. The bad news is from the looks of this post, I don't think you're going to have much luck. It sounds like this list is not highly targeted and won't get a high open-rate. Also, there is no landing in "inbox" 10% It's either you are in the clear or you're blacklisted. With cold email marketing your walking on eggshells the whole campaign, so the chances of running email lists long term without a high open rate makes the odds slim.