Thanks for the answer.
I removed this log from the spamexperts service, at first I asked them for help thinking that it could be the block there, but that was their response:
Please note the message was accepted by us/our filtering servers based on the whitelist rule in place, but it was bounced on the destination mail server on the recipient side. This is not related to us and needs to be further checked and resolved on that destination server
Further checking the logs for the message we can see:
2021-01-27 20:42:40  1l4qi8-0005KJ-5J DMARC results: spf_domain=em9115.b2bnetwork.net.br dmarc_domain=b2bnetwork.net.br spf_align=yes dkim_align=yes enforcement='Accept'
2021-01-27 20:42:40  1l4qi8-0005KJ-5J H=xtrwqnvh.outbound-mail.sendgrid.net [184.108.40.206] I=[220.127.116.11]:25 Warning: DMARC DEBUG: 'accept' for b2bnetwork.net.br - Accept
2021-01-27 20:42:43  1l4qi8-0005KJ-5J <= email@example.com H=xtrwqnvh.outbound-mail.sendgrid.net [18.104.22.168] I=[22.214.171.124]:25 P=esmtps CV=no PRX=126.96.36.199 S=40399 DKIM=b2bnetwork.net.br id=70D98B7376CF47089679D2D19D5213DA@b2bnetwork.com.br
2021-01-27 20:42:44  1l4qi8-0005KJ-5J [188.8.131.52] SSL verify error: certificate name mismatch: DN="/CN=plesk03-insidesign.com.br" H="mail.swfast.com.br"
2021-01-27 20:42:44  1l4qi8-0005KJ-5J ** firstname.lastname@example.org R=spamexperts T=remote_smtp_batv H=mail.swfast.com.br [184.108.40.206] I=[220.127.116.11] CV=no: SMTP error from remote mail server after MAIL FROM:<email@example.com> SIZE=41619: 550 Sender is not allowed.
2021-01-27 20:42:45  1l4qiC-0005Rj-SB <= <> R=1l4qi8-0005KJ-5J U=Debian-exim P=local S=6371
2021-01-27 20:42:45  1l4qi8-0005KJ-5J Completed
So, based on the logs and the screenshot attached with the extra query rules added from the Columns to be displayed option, that there is another local rule on the recipient side, using some extra checkups, that are blocking that sender
MAIL FROM:<firstname.lastname@example.org> SIZE=41619: 550 Sender is not allowed.
We cannot see those rules and we do not have control of them, so this is something the recipient needs to resolve.
We do not recommend having any extra DNSBLs or filter checks applied on the already filtered messages on the destination mail servers.
This client uses a third-party CRM that is sending the password to him and bouncing the server.
I hope I have explained the case better.