Nearly all email systems at some point have delivery issues because their sending IPs or domains are included
on a blocklist. This includes Email Sender Providers and network operators. Depending on where mail is
blocked, these listings can trigger a panic reaction inside the blocked company. Therefore, understanding the
established procedures defining how to triage and respond to the situation is important to ensure a timely
and effective resolution. This document specifically addresses delivery failures due to active blocks placed
against a sender’s IP address or domain.