Typically IPs get blacklisted when the the outbound relay servers send out spam and this is detected/ noticed by worldwide blacklist resources. In the case of Mithi SkyConnect, mail access servers are protected from sending spam originating from the network and all outbound traffic is routed via SecureMailflow and is scanned for viruses to ensure that only clean mail leave the periphery. This reduces the chance of IP blacklisting down to near zero.
Since we moved to this architecture, we’ve stopped worrying about blacklisting of our outbound IPs. Another thing we care about is the DNS hygiene of our customers. We ensure proper configuration of SPF, DKIM etc to ensure that the reputation of our customers’ domains is very high.