Postfix не может отправлять письма на gmail - уведомление о недоставке отправителя

Возникли проблемы с отправкой писем в Gmail с помощью Postfix. Ниже мой журнал:

Nov 24 15:07:02 ubuntu-4gb-fsn1-1 postfix/pickup[101539]: 4C99C4225A: uid=33 from=<www-data>
Nov 24 15:07:02 ubuntu-4gb-fsn1-1 postfix/cleanup[101916]: 4C99C4225A: message-id=<20201124140702.4C99C4225A@ubuntu-4gb-fsn1-1>
Nov 24 15:07:02 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 4C99C4225A: from=<www-data@my-domain.com>, size=329, nrcpt=1 (queue active)
Nov 24 15:07:03 ubuntu-4gb-fsn1-1 postfix/smtp[101918]: 4C99C4225A: to=<recipient@yahoo.co.uk>, relay=mx-eu.mail.am0.yahoodns.net[188.125.72.74]:25, d
elay=0.91, delays=0.02/0.01/0.34/0.52, dsn=2.0.0, status=sent (250 ok dirdel)
Nov 24 15:07:03 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 4C99C4225A: removed
Nov 24 15:07:58 ubuntu-4gb-fsn1-1 postfix/pickup[101539]: 9552D4225A: uid=33 from=<www-data>
Nov 24 15:07:58 ubuntu-4gb-fsn1-1 postfix/cleanup[101916]: 9552D4225A: message-id=<20201124140758.9552D4225A@ubuntu-4gb-fsn1-1>
Nov 24 15:07:58 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 9552D4225A: from=<www-data@my-domain.com>, size=332, nrcpt=1 (queue active)
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/smtp[101918]: 9552D4225A: to=<recipient@googlemail.com>, relay=gmail-smtp-in.l.google.com[2a00:1450:400c:c0c::1b]:25, delay=0.76, delays=0.01/0/0.13/0.61, dsn=5.7.1, status=bounced (host gmail-smtp-in.l.google.com[2a00:1450:400c:c0c::1b] said: 550-5.7.1 [2a01:4f8:c010:3127::1] Our system has detected that this message does 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1 authentication. Please review 550-5.7.1  https://support.google.com/mail/?p=IPv6AuthError for more information 550 5.7.1 . n11si2614598wma.157 - gsmtp (in reply to end of DATA command))
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/cleanup[101916]: 5B1304225D: message-id=<20201124140759.5B1304225D@ubuntu-4gb-fsn1-1>
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/bounce[101930]: 9552D4225A: sender non-delivery notification: 5B1304225D
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 5B1304225D: from=<>, size=3011, nrcpt=1 (queue active)
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 9552D4225A: removed
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/local[101931]: 5B1304225D: to=<www-data@my-domain.com>, relay=local, delay=0.01, delays=0/0.01/0/0, dsn=2.0.0, status=sent (delivered to mailbox)
Nov 24 15:07:59 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 5B1304225D: removed
Nov 24 15:20:21 ubuntu-4gb-fsn1-1 postfix/pickup[101539]: 714A94225D: uid=33 from=<www-data>
Nov 24 15:20:21 ubuntu-4gb-fsn1-1 postfix/cleanup[102121]: 714A94225D: message-id=<20201124142021.714A94225D@ubuntu-4gb-fsn1-1>
Nov 24 15:20:21 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 714A94225D: from=<www-data@my-domain.com>, size=328, nrcpt=1 (queue active)
Nov 24 15:20:21 ubuntu-4gb-fsn1-1 postfix/smtp[102123]: 714A94225D: host mx1.pub.mailpod9-cph3.one.com[185.164.14.118] said: 450 4.7.1 138.119.249.183 temporary greylisted by CYREN IP reputation (in reply to MAIL FROM command)
Nov 24 15:20:21 ubuntu-4gb-fsn1-1 postfix/smtp[102123]: 714A94225D: lost connection with mx1.pub.mailpod9-cph3.one.com[185.164.14.118] while sending RCPT TO
Nov 24 15:20:22 ubuntu-4gb-fsn1-1 postfix/smtp[102123]: 714A94225D: to=<contact@lauthiamkok.net>, relay=mx3.pub.mailpod9-cph3.one.com[185.164.14.120]:25, delay=0.92, delays=0.02/0.02/0.82/0.07, dsn=4.7.1, status=deferred (host mx3.pub.mailpod9-cph3.one.com[185.164.14.120] said: 450 4.7.1 138.119.249.183 temporary greylisted by CYREN IP reputation (in reply to MAIL FROM command))
Nov 24 15:27:09 ubuntu-4gb-fsn1-1 postfix/qmgr[65515]: 714A94225D: from=<www-data@my-domain.com>, size=328, nrcpt=1 (queue active)
Nov 24 15:27:10 ubuntu-4gb-fsn1-1 postfix/smtp[102169]: 714A94225D: host mx3.pub.mailpod9-cph3.one.com[185.164.14.120] said: 450 4.7.1 138.119.249.183 temporary greylisted by CYREN IP reputation (in reply to MAIL FROM command)

Nov 24 15:27:10 ubuntu-4gb-fsn1-1 postfix/smtp[102169]: 714A94225D: lost connection with mx3.pub.mailpod9-cph3.one.com[185.164.14.120] while sending RCPT TO
Nov 24 15:27:10 ubuntu-4gb-fsn1-1 postfix/smtp[102169]: 714A94225D: to=<contact@other-email.net>, relay=mx2.pub.mailpod9-cph3.one.com[185.164.14.119]:25, delay=409, delays=408/0.02/0.57/0.05, dsn=4.7.1, status=deferred (host mx2.pub.mailpod9-cph3.one.com[185.164.14.119] said: 450 4.7.1 138.119.249.183 temporary greylisted by CYREN IP reputation (in reply to MAIL FROM command))
(END)

Вы можете видеть, что с Yahoo нет проблем. Но вы получаете уведомление о недоставке отправителя для Gmail.

Есть идеи, почему?

Моя конфигурация Postfix:

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level=may

smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level=may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = ubuntu-4gb-fsn1-1
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = my-domain.com, $myhostname, ubuntu-4gb-fsn1-1, localhost.localdomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only
inet_protocols = all