How to fix stat=Deferred: Name server: ironport.axsel-group.ru.: host name lookup failure in sendmail?

Question

send mail

Good afternoon. I'm trying to send an email via sendmail, I'm getting the following error:

Jun 22 16:06:18 a4 sm-ml[46264]: 15MD61OW044939: to=<[email protected]>, delay=00:00:17, xdelay=00:00:00, mailer=esmtp, pri=624976, relay=ironport.axsel-group.ru. [84.204.47.75], dsn=4.0.0, stat=Deferred: Name server: ironport.axsel-group.ru.: host name lookup failure

sendmail.cf

divert(0)
VERSIONID(`$FreeBSD: src/etc/sendmail/freebsd.mc,v 1.34.2.1 2007/11/22 16:19:40 gshapiro Exp $')
OSTYPE(freebsd6)
DOMAIN(generic)

FEATURE(access_db , `hash -o -T /etc/mail/access')
FEATURE(blacklist_recipients)
FEATURE(local_lmtp)
FEATURE(mailertable, `hash -o /etc/mail/mailertable')
FEATURE(virtusertable, `hash -o /etc/ mail/virtusertable')

define(`confCW_FILE', `-o /etc/mail/local-host-names')

DAEMON_OPTIONS(`Name=IPv4, Family=inet')
DAEMON_OPTIONS(`Name=IPv6, Family=inet6, Modifiers =O')

define(`confDH_PARAMETERS',`/etc/mail/certs/dhparams.pem')
define(`confBIND_OPTS', `WorkAroundBrokenAAAA -RECURSE')
define(`confNO_RCPT_ACTION', `add-to-undisclosed')
define(`confPRIVACY_FLAGS', `authwarnings,noexpn,novrfy')

FEATURE(`nocanonify', `canonify_hosts')
FEATURE(`accept_unresolvable_domains')

MAILER(local)
MAILER( smtp)

INPUT_MAIL_FILTER(`dkim-filter', `S=inet:[email protected]')dnl