> Then either you didn’t configure your server correctly or you were trying to run a server on an IP address that’s part of a blacklisted netblock (e.g. residential).
This is frequently the case but not always. Sometimes you don't have any server issues, and originating IP is totally fine, but your messages are 250-accepted then somehow just disappear into the void without reaching the recipient mailbox (not even the "spam" folder).
Fortunately, it's rare (in my experience), but super annoying when this happens, because with FAANGs there's absolutely no way to reach out for any technical support (unless you know someone who works there and they can help you).
This is frequently the case but not always. Sometimes you don't have any server issues, and originating IP is totally fine, but your messages are 250-accepted then somehow just disappear into the void without reaching the recipient mailbox (not even the "spam" folder).
Fortunately, it's rare (in my experience), but super annoying when this happens, because with FAANGs there's absolutely no way to reach out for any technical support (unless you know someone who works there and they can help you).