I had a long back and forth with my host and besides a mistake in the server address, I had not filled in the dedicated sender email address, because I did not have to do that in the previous WP email post setting.
So maybe that helps
Hi, I have the same problem . I have 6 websites on WP and with 5 I have no trouble with the email posting feature but the last one did not offer the WP email post feature anymore but when I down loaded Postie it did not work either.
I can not get it to run 🙁