Hi,
since two weeks I have the same issue. Before that, everything was working fine. My newsletter subscripers with outlook and hotmail domain do not receive my newsletter. I am not sure whether during the last two weeks you have released a new update and that is why it is not working anymore.
I tested the spam score on mail-tester.com and the score was 9. So this cannot be the issue as the newsletter even not reaches the spam folder of outlook or hotmail inbox. When I try sending a newsletter preview on a hotmail or outlook email address I receive the following message on my inbox
SMTP error from remote mail server after MAIL FROM:<info@<mydomainname>.de> SIZE=70010:
host mx4.hotmail.com [65.55.37.120]: 550 SC-001 (COL004-MC4F16) Unfortunately, messages from 217.160.95.218 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors.
I have a private domain and if I try sending out an email to a outlook or hotmail email address using the email client of my provider 1&1, then the email is successfully sent. So I think there is an issue only when I use the mailpoet plugin in WordPress and sent an email using your plugin.
Any help would be appreciated. Thanks a lot for your answer.
Lihas