We have an error with a various domains with sending e-mails. Our server returns with the message :
Jan 22 10:15:00 correu postfix/smtp: 5F17239EC02C: to=<firstname.lastname@example.org>, relay=mail.tenisgimeno.com[220.127.116.11]:25, delay=0.18, delays=0/0/0.1/0.07, dsn=5.0.0, status=bounced (host mail.tenisgimeno.com[18.104.22.168] said: 501 Domain must resolve (in reply to MAIL FROM command))
I don't know what is the problem. Any idea?