Since few months I am not able to send epub files to my kindle. When I try it in the usual way I used to do in the past the proces starts but at the end an error mesagge shows up like the one below.
Starting job: Sending Cora to the following email address
x.x_q9XnbR@kindle.com
Sending failed...
Traceback (most recent call last):
File "calibre\gui2\email.py", line 48, in run
File "calibre\gui2\email.py", line 137, in sendmail
File "calibre\utils\smtp.py", line 163, in sendmail
File "calibre\utils\smtp.py", line 143, in sendmail_direct
OSError: Failed to send mail: SMTPRecipientsRefused({'x.x_q9XnbR@kindle.com': (550, b'5.7.1 IP address blacklisted by recipient')})[/B][/B][/B]