Hello Guys,
i've installed and configured Postifx on Centos 7.

i managed to add relay host of office 365, which means every mail i send, is sent by office 365 mailbox.
now for my issue,
the default "from:" is localhost and i didn't find how to change it, which means in order to send email i need to write as following: "mail -s "subject" -r "office 365 mailbox" "@example.com"

if i send mail in that syntax, it's work, but if i don't add "-r @office365" it tries to authenticate to office 365 mailbox with root

another issue is that i want to forward all mails being sent to root trough this office 365 relay to external mailbx.
I've changed the /etc/aliases but still has issue for authentication

Aug 28 10:05:39 127 postfix/qmgr[2448]: 9E83D6001226: from=<>, size=2960, nrcpt=1 (queue active)
Aug 28 10:05:39 127 postfix/qmgr[2448]: 9D2A8607E6CD: removed
Aug 28 10:05:48 127 postfix/smtp[4445]: 9E83D6001226: to=<test@example.com>, orig_to=<root@localhost>, relay=smtp.office365.com[40.101.72.146]:587, delay=8.5, delays=0/0.02/3.2/5.2, dsn=5.7.60, status=bounced (host smtp.office365.com[40.101.72.146] said: 550 5.7.60 SMTP; Client does not have permissions to send as this sender [DB6PR0602MB3302.eurprd06.prod.outlook.com] (in reply to end of DATA command))