Please provide the logs of such a mail. You can see the complete log for a mail by double clicking on it in the tracking center.
Thanks you for your answer!
1. Log from node1:
Jul 20 06:46:32 mailgw postfix/smtpd[12074]: warning: hostname bizcloud-uni-frankfurt.de does not resolve to address 46.101.103.88: Name or service not known
Jul 20 06:46:32 mailgw postfix/smtpd[12074]: connect from unknown[46.101.103.88]
Jul 20 06:46:35 mailgw postfix/smtpd[12074]: 11FF4810B7: client=unknown[46.101.103.88]
Jul 20 06:46:35 mailgw postfix/cleanup[11507]: 11FF4810B7: message-id=<
20210719234754.1C0B264EC6A870D6@zenbuddy.co.uk>
Jul 20 06:46:35 mailgw postfix/smtpd[12074]: disconnect from unknown[46.101.103.88] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Jul 20 06:46:35 mailgw postfix/qmgr[28422]: 11FF4810B7: from=<
china@zenbuddy.co.uk>, size=25297, nrcpt=1 (queue active)
Jul 20 06:46:35 mailgw pmg-smtp-filter[12347]: 8116760F60EDB792E6: new mail message-id=<
20210719234754.1C0B264EC6A870D6@zenbuddy.co.uk>#012
Jul 20 06:46:37 mailgw pmg-smtp-filter[12347]: 8116760F60EDB792E6: SA score=1/5 time=1.665 bayes=0.00 autolearn=no autolearn_force=no hits=BAYES_00(-1.9),HTML_FONT_SIZE_LARGE(0.001),HTML_MESSAGE(0.001),KAM_COUK(0.85),KAM_DMARC_STATUS(0.01),MIME_HTML_ONLY(0.1),RDNS_NONE(0.793),SPF_HELO_NONE(0.001),SPF_SOFTFAIL(0.665),TO_NO_BRKTS_NORDNS_HTML(1.206),URIBL_BLOCKED(0.001),URI_WP_HACKED(0.001)
Jul 20 06:46:37 mailgw pmg-smtp-filter[12347]: 8116760F60EDB792E6: block mail to <
andh@atvina.vn>
(rule: Blacklist)
Jul 20 06:46:37 mailgw pmg-smtp-filter[12347]: 8116760F60EDB792E6: processing time: 1.716 seconds (1.665, 0.026, 0)
Jul 20 06:46:37 mailgw postfix/lmtp[12095]: 11FF4810B7: to=<
andh@atvina.vn>, relay=127.0.0.1[127.0.0.1]:10024, delay=3.9, delays=2.2/0/0/1.7, dsn=2.7.0, status=sent (250 2.7.0 BLOCKED (8116760F60EDB792E6))
Jul 20 06:46:37 mailgw postfix/qmgr[28422]: 11FF4810B7: removed
2. Log from node2:
Jul 20 09:22:40 mailgw2 postfix/smtpd[18462]: warning: hostname bizcloud-uni-frankfurt.de does not resolve to address 46.101.103.88: Name or service not known
Jul 20 09:22:40 mailgw2 postfix/smtpd[18462]: connect from unknown[46.101.103.88]
Jul 20 09:22:42 mailgw2 postfix/smtpd[18462]: B28FB161F2E: client=unknown[46.101.103.88]
Jul 20 09:22:42 mailgw2 postfix/cleanup[15955]: B28FB161F2E: message-id=<
20210720020315.4F7FE64EB19924ED@zenbuddy.co.uk>
Jul 20 09:22:43 mailgw2 postfix/smtpd[18462]: disconnect from unknown[46.101.103.88] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Jul 20 09:22:43 mailgw2 postfix/qmgr[26505]: B28FB161F2E: from=<
china@zenbuddy.co.uk>, size=25321, nrcpt=1 (queue active)
Jul 20 09:22:43 mailgw2 pmg-smtp-filter[18309]: 161F6260F6337340709: new mail message-id=<
20210720020315.4F7FE64EB19924ED@zenbuddy.co.uk>#012
Jul 20 09:22:49 mailgw2 pmg-smtp-filter[18309]: 161F6260F6337340709: SA score=1/5 time=5.763 bayes=0.00 autolearn=no autolearn_force=no hits=AWL(-0.057),BAYES_00(-1.9),HTML_FONT_SIZE_LARGE(0.001),HTML_MESSAGE(0.001),KAM_COUK(0.85),KAM_DMARC_STATUS(0.01),MIME_HTML_ONLY(0.1),RDNS_NONE(0.793),SPF_HELO_NONE(0.001),SPF_SOFTFAIL(0.665),TO_NO_BRKTS_NORDNS_HTML(1.206),URIBL_BLOCKED(0.001),URI_WP_HACKED(0.001)
Jul 20 09:22:49 mailgw2 postfix/smtpd[17227]: connect from localhost.localdomain[127.0.0.1]
Jul 20 09:22:49 mailgw2 postfix/smtpd[17227]: 1300F162194: client=localhost.localdomain[127.0.0.1], orig_client=unknown[46.101.103.88]
Jul 20 09:22:49 mailgw2 postfix/cleanup[15955]: 1300F162194: message-id=<
20210720020315.4F7FE64EB19924ED@zenbuddy.co.uk>
Jul 20 09:22:49 mailgw2 postfix/smtpd[17227]: disconnect from localhost.localdomain[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 commands=5
Jul 20 09:22:49 mailgw2 pmg-smtp-filter[18309]: 161F6260F6337340709: accept mail to <
info@innedvn.com> (1300F162194)
(rule: default-accept)
Jul 20 09:22:49 mailgw2 postfix/qmgr[26505]: 1300F162194: from=<
china@zenbuddy.co.uk>, size=26685, nrcpt=1 (queue active)
Jul 20 09:22:49 mailgw2 pmg-smtp-filter[18309]: 161F6260F6337340709: processing time: 5.816 seconds (5.763, 0.026, 0)
Jul 20 09:22:49 mailgw2 postfix/lmtp[13779]: B28FB161F2E: to=<
info@innedvn.com>, relay=127.0.0.1[127.0.0.1]:10024, delay=7.7, delays=1.9/0/0/5.8, dsn=2.5.0, status=sent (250 2.5.0 OK (161F6260F6337340709))
Jul 20 09:22:49 mailgw2 postfix/qmgr[26505]: B28FB161F2E: removed
Jul 20 09:22:49 mailgw2 postfix/smtp[10689]: 1300F162194: to=<
info@innedvn.com>, relay=103.57.223.50[103.57.223.50]:25, delay=0.2, delays=0/0/0.05/0.14, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 38857C00FD416)
Jul 20 09:22:49 mailgw2 postfix/qmgr[26505]: 1300F162194: removed
Node2 using default-accept.