I get the same result:
nc mail.xxxxxxxx.com 25
220-***************************************************************************
220-*********************************************************************
220 *******************
helo haxor@home.com
250 xxxxx.xxxxxx.com Hello haxor@home.com [154.xxx.xx.70]
MAIL FROM: openvasvt@nyx
250 OK
RCPT TO: openvasvt@example.com
550 “Sorry, you are sending to/from an address that has been blacklisted”
^C
nc mail.xxxxxxxx.com 587
220-xxxxxx.xxxxxxxx.com ESMTP Exim 4.93 #2 Sat, 19 Sep 2020 04:51:57 -0500
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
helo haxor@home.com
250 gator4154.hostgator.com Hello haxor@home.com [154.xxx.xx.70]
MAIL FROM: openvasvt@nyx
250 OK
RCPT TO: openvasvt@example.com
550 SMTP AUTH is required for message submission on port 587