Some users of my MIAB report their emails get rejected when emailing to clients. Looking at the messages, it appears those clients use Microsoft as a back-end for the business email. This has been going on quite some time now and both myself as well as my MIAB users went through the “un-listing” process a few times, which sometimes works, but more often than not either the application for un-listing is rejected or their blocks return after a while. The Microsoft automated email claims there has been suspicious traffic from our IP, but when I inquire with them if they can show me logs (because there is nothing suspicious to see in my logs), there is no more reply from their support agents.
I am running my MIAB on a Linode server in Tokyo and there is no spamming going on.
So, given that is is troublesome for my MIAB users to do their jobs, when their work emails bounce all the time, and with Microsoft not being supportive, I am thinking of options. Is there a different hoster you would recommend, for example?
I think it might be a little naive to say that there is no spamming going on. Spam is about IP reputation (amongst other things) so if your ISP has a IP block of say /24 or larger and one of those IPs is spamming people then certain mail lists block that entire subnet as spammy.