aaronsmith
The client is Windows 10 Email app version 16005.14326.20970.0
I didn’t see anything different in Postfix log, here it is (email addressess changed):
12/10/2022 22:10:20 info 25FB380A2D: removed
12/10/2022 22:10:20 info 25FB380A2D: to=<XXX@xxx.com.br>, relay=smtp.mailgun.org[34.150.216.144]:587, delay=8.1, delays=6.9/0.08/0.56/0.52, dsn=2.0.0, status=sent (250 Great success)
12/10/2022 22:10:19 info Trusted TLS connection established to smtp.mailgun.org[34.150.216.144]:587: TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256
12/10/2022 22:10:18 info 25FB380A2D: from=<XXX@ttt.com.br>, size=1231822, nrcpt=1 (queue active)
12/10/2022 22:10:18 info disconnect from mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network[172.22.1.248] ehlo=1 auth=1 mail=1 rcpt=1 data=1 quit=1 commands=6
12/10/2022 22:10:14 info 25FB380A2D: message-id=<>
12/10/2022 22:10:14 info 25FB380A2D: replace: header Received: from 7000d0f85d88 (mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network [172.22.1.248])??(Authenticated sender: XXX@ttt.com.br)??by mail.trezzuri.com.br (Postcow from mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network[172.22.1.248]; from=<XXX@ttt.com.br> to=<XXX@xxx.com.br> proto=ESMTP helo=<7000d0f85d88>: Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPA id 25FB380A2D??for <XXX@xxx.com.br>; Wed, 12 Oct 2022 22:10:11 -0300 (-03)
12/10/2022 22:10:14 info 25FB380A2D: client=mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network[172.22.1.248], sasl_method=PLAIN, sasl_username=XXX@ttt.com.br