I have tried to send an email to email@example.com from different email accounts. Everytime I receive a delivery failure error message back like:
Error transferring to mail.OPENNTF.ORG; SMTP Protocol Returned a Permanent Error 554 Connection from www.xxx.yyy.zzz rejected for policy reasons. Host found in DNS blacklist at bl.spamcop.net
It seems that this problem is located at openbtf.org.
Have a nice day