Looking for current MTA IP "warm up" best practices please... We are a niche email hosting company for commercial/regulated corporate entities with a strong anti-bulk-mail-sending AUP. Our existing MTA IPs have very positive reputations. All (but one) of our customers sign email with DKIM, and we have provisioned strong SPF and DMARC records for all of our customers' domains. We monitor with Dmarcian and are registered with more than twenty email feedback loop programs.
We went to deploy a new outbound MTA server ~two months ago, with an IP address that we have owned for about two years but hadn't used, and which at the time we confirmed was not on any blacklists, nor listed in any of the sender reputation services. We thought the IP would be deemed clean, especially because the PTR record points to the same domain as our other MTAs, and so we put this new MTA in production on a long weekend so it would be sending out only small volumes of email. This strategy in the past has worked well for us, but not this time. We found that as soon as we started shifting a small portion of our outbound mail traffic to this new MTA, the MTA's IP address started getting blocked outright by Microsoft and others. So we stopped, took the new MTA out of production, and have spent the last two months trying to determine what we did wrong. What we have found is that it seems nowadays new IP addresses need to be "warmed up" with the majors. But 1) we haven't found any recent warm up guides we deem reliable, and 2) this IP is on Microsoft's and other's block lists. Microsoft won't remove the IP from their block list, so we seem to be in a bit of a Catch-22 in that we can't "warm-up" the IP if it already blocked, and from what we've read, it seems we can't get the IP removed from block lists until we start sending legitimate mail through the IP -- which of course we cannot do with customers' legitimate email. So, asking what you all would recommend we do with this IP, and how best we should warm up a new IP in future to avoid finding ourselves in this same situation again. Regards, and TIA, Mark ___________________________________________ L. Mark Stone, Mission Critical Email LLC
_______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
