I've got a new installation of Mailman 3 setup, however I am having some issues I'm not sure how to troubleshoot.

Mailman is successfully sending invite emails however user messages sent to the list are not being sent to subscribers. Also in Hyperkitty none of my test messages to the list are showing up in the archive.

I am using Postfix with an SMTP relay hosted at Brevo.com (formally sendinblue). Brevo's logs show the message getting rejected

Log from brevo.com (SMPT Relay) Sent on 17-11-2024 21:49:16 From listmember@gmail.com To listmember@gmail.com Message ID<CAPesOD1y0fEaG=GFodz=Lgs1m_hqRErPnQcpXCNtKsBbJ= BJ7Q@mail.gmail.com>

17-11-2024 21:49:16 Sending has been rejected because the sender you used listmember@gmail.com is not valid. Validate your sender or authenticate your domain

...

...

Postfix main.cf

# See /usr/share/postfix/main.cf.dist for a commented, more complete version

# Debian specific: Specifying a file name will cause the first # line of that file to be used as the name. The Debian default # is /etc/mailname. #myorigin = /etc/mailname

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 3.6 on # fresh installs. compatibility_level = 3.6

# 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_session_cache_database = btree:${data_directory}/smtp_scache

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination myhostname = list.louisvillecommunitygrocery.com alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases myorigin = $myhostname mydestination = $myhostname, list.louisvillecommunitygrocery.com, localhost.louisvillecommunitygrocery.com, , localhost mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all inet_protocols = all

# Mailman3 configs # Support the default VERP delimiter. recipient_delimiter = +

unknown_local_recipient_reject_code = 550 owner_request_special = no

transport_maps = hash:/opt/mailman/mm/var/data/postfix_lmtp local_recipient_maps = hash:/opt/mailman/mm/var/data/postfix_lmtp relay_domains = hash:/opt/mailman/mm/var/data/postfix_domains

#SMPT Relay Brevo relayhost = [smtp-relay.sendinblue.com]:587 smtp_sasl_auth_enable = yes smtp_sasl_security_options = noanonymous smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_tls_security_level = encrypt smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

*In closing*, can anyone point me in the right direction for further troubleshooting on this issue?

Thank you, Paul 'Arte Chambers' Robey