this is one you can see that has failed and been sent via outlook on the rds server
Aug 23 11:40:35 mg1 postfix/smtpd[31999]: connect from zimbra1.msqpartners.com[142.93.37.1]
Aug 23 11:40:35 mg1 postfix/smtpd[31999]: Anonymous TLS connection established from zimbra1.msqpartners.com[142.93.37.1]: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256
Aug 23 11:40:35 mg1 postfix/smtpd[31999]: B0AB460BF7: client=zimbra1.msqpartners.com[142.93.37.1]
Aug 23 11:40:35 mg1 postfix/cleanup[32001]: B0AB460BF7: message-id=<018c01d79813$afda0320$0f8e0960$@cshw.co.uk>
Aug 23 11:40:35 mg1 postfix/qmgr[1263]: B0AB460BF7: from=<
jo.twemlow@cshw.co.uk>, size=6572, nrcpt=1 (queue active)
Aug 23 11:40:35 mg1 postfix/smtpd[31999]: disconnect from zimbra1.msqpartners.com[142.93.37.1] ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
Aug 23 11:40:35 mg1 pmg-smtp-filter[31932]: 60C1361238933BBFEE: new mail message-id=<018c01d79813$afda0320$0f8e0960$@cshw.co.uk>#012
Aug 23 11:40:35 mg1 pmg-smtp-filter[31932]: 60C1361238933BBFEE: adding disclaimer failed (rule: CSHW Disclaimer)
Aug 23 11:40:35 mg1 pmg-smtp-filter[31932]: 60C1361238933BBFEE: adding disclaimer failed (rule: CSHW Disclaimer)
Aug 23 11:40:35 mg1 postfix/smtpd[32006]: connect from localhost[127.0.0.1]
Aug 23 11:40:35 mg1 postfix/smtpd[32006]: C2F1760C67: client=localhost[127.0.0.1], orig_client=zimbra1.msqpartners.com[142.93.37.1]
Aug 23 11:40:35 mg1 postfix/cleanup[32023]: C2F1760C67: message-id=<018c01d79813$afda0320$0f8e0960$@cshw.co.uk>
Aug 23 11:40:35 mg1 postfix/qmgr[1263]: C2F1760C67: from=<
jo.twemlow@cshw.co.uk>, size=6762, nrcpt=1 (queue active)
Aug 23 11:40:35 mg1 postfix/smtpd[32006]: disconnect from localhost[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 commands=5
Aug 23 11:40:35 mg1 pmg-smtp-filter[31932]: 60C1361238933BBFEE: accept mail to <
oliverholroyd@googlemail.com> (C2F1760C67) (rule: default-accept)
Aug 23 11:40:35 mg1 pmg-smtp-filter[31932]: 60C1361238933BBFEE: processing time: 0.074 seconds (0, 0.015, 0)
Aug 23 11:40:35 mg1 postfix/lmtp[32002]: B0AB460BF7: to=<
oliverholroyd@googlemail.com>, relay=127.0.0.1[127.0.0.1]:10023, delay=0.12, delays=0/0/0.04/0.08, dsn=2.5.0, status=sent (250 2.5.0 OK (60C1361238933BBFEE))
Aug 23 11:40:35 mg1 postfix/qmgr[1263]: B0AB460BF7: removed
Aug 23 11:40:36 mg1 postfix/smtp[32007]: C2F1760C67: to=<
oliverholroyd@googlemail.com>, relay=gmail-smtp-in.l.google.com[66.102.1.26]:25, delay=0.43, delays=0.05/0/0.08/0.31, dsn=2.0.0, status=sent (250 2.0.0 OK 1629718836 q4si6908763wrm.312 - gsmtp)
Aug 23 11:40:36 mg1 postfix/qmgr[1263]: C2F1760C67: removed
and this one was sent via zimbra mail on the rds server
Aug 23 12:51:21 mg1 postfix/smtpd[549]: connect from zimbra1.msqpartners.com[142.93.37.1]
Aug 23 12:51:21 mg1 postfix/smtpd[549]: Anonymous TLS connection established from zimbra1.msqpartners.com[142.93.37.1]: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256
Aug 23 12:51:21 mg1 postfix/smtpd[549]: 316CD60C6A: client=zimbra1.msqpartners.com[142.93.37.1]
Aug 23 12:51:21 mg1 postfix/cleanup[408]: 316CD60C6A: message-id=<
417131024.2707.1629723080980.JavaMail.zimbra@cshw.co.uk>
Aug 23 12:51:21 mg1 postfix/qmgr[1263]: 316CD60C6A: from=<
jo.twemlow@cshw.co.uk>, size=3672, nrcpt=1 (queue active)
Aug 23 12:51:21 mg1 postfix/smtpd[549]: disconnect from zimbra1.msqpartners.com[142.93.37.1] ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
Aug 23 12:51:21 mg1 pmg-smtp-filter[503]: 60C71612399C93D07E: new mail message-id=<
417131024.2707.1629723080980.JavaMail.zimbra@cshw.co.uk>#012
Aug 23 12:51:21 mg1 pmg-smtp-filter[503]: 60C71612399C93D07E: added disclaimer (rule: CSHW Disclaimer)
Aug 23 12:51:21 mg1 pmg-smtp-filter[503]: 60C71612399C93D07E: added disclaimer (rule: CSHW Disclaimer)
Aug 23 12:51:21 mg1 postfix/smtpd[413]: connect from localhost[127.0.0.1]
Aug 23 12:51:21 mg1 postfix/smtpd[413]: 45DB060C75: client=localhost[127.0.0.1], orig_client=zimbra1.msqpartners.com[142.93.37.1]
Aug 23 12:51:21 mg1 postfix/cleanup[463]: 45DB060C75: message-id=<
417131024.2707.1629723080980.JavaMail.zimbra@cshw.co.uk>
Aug 23 12:51:21 mg1 postfix/qmgr[1263]: 45DB060C75: from=<
jo.twemlow@cshw.co.uk>, size=7341, nrcpt=1 (queue active)
Aug 23 12:51:21 mg1 postfix/smtpd[413]: disconnect from localhost[127.0.0.1] ehlo=1 xforward=1 mail=1 rcpt=1 data=1 commands=5
Aug 23 12:51:21 mg1 pmg-smtp-filter[503]: 60C71612399C93D07E: accept mail to <
oliverholroyd@googlemail.com> (45DB060C75) (rule: default-accept)
Aug 23 12:51:21 mg1 pmg-smtp-filter[503]: 60C71612399C93D07E: processing time: 0.082 seconds (0, 0.019, 0)
Aug 23 12:51:21 mg1 postfix/lmtp[409]: 316CD60C6A: to=<
oliverholroyd@googlemail.com>, relay=127.0.0.1[127.0.0.1]:10023, delay=0.13, delays=0/0/0.05/0.09, dsn=2.5.0, status=sent (250 2.5.0 OK (60C71612399C93D07E))
Aug 23 12:51:21 mg1 postfix/qmgr[1263]: 316CD60C6A: removed
Aug 23 12:51:21 mg1 postfix/smtp[414]: 45DB060C75: to=<
oliverholroyd@googlemail.com>, relay=gmail-smtp-in.l.google.com[173.194.76.27]:25, delay=0.67, delays=0.05/0/0.18/0.44, dsn=2.0.0, status=sent (250 2.0.0 OK 1629723081 g2si16085257wmc.167 - gsmtp)
Aug 23 12:51:21 mg1 postfix/qmgr[1263]: 45DB060C75: removed