[The prospect who got himself blacklisted] thought he could solve all his problems if he switched to MailChimp, because we apparently have a good reputation, and because he thought we had some kind of secret-handshake arrangement with ISPs (actually, that's not the case---they'll blacklist anybody that generates too many spam complaints).Ben @ MailChimp is 100% correct. ISPs will block and blacklist you, regardless of who your email service provider (ESP) is, or what IP address you send from. And they're smart enough to figure it out when you change ESPs. If they blocked you at the other ESP, it will take anywhere from immediately to very soon before they find you and block you at your new home. Your reputation follows you. You'll hit the same spamtraps, have the same volume of complaints. Since these are what drive ISP blocks, switching ESPs isn't going to magically wash all that away.
ESPs, their clients, and ISP blocking
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