Mailbox MX IP banned from free.fr
This is the mail system at host mx2a.mailbox.org.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
<--firstname.lastname@example.org>: host mx1.free.fr[220.127.116.11] said: 554 too many
errors detected from your IP (18.104.22.168), please visit
http://postmaster.free.fr/ (in reply to DATA command)