PostFix: Reason:530 5.5.1 Authentication Required

I am trying to setup PostFix to be my local SMTP replay for all my services to send alerts to myself.

However, I am not able to authenticate with the Zoho SMTP service to send messages.

The log says the following:

Sep 22 13:15:29 core postfix/qmgr[168993]: 563E13FEC9: from=<root@core.HOST>, size=374, nrcpt=1 (queue active)

Sep 22 13:15:29 core postfix/smtp[169236]: host smtp.zeptomail.com[165.173.183.10] offers SMTPUTF8 support, but not 8BITMIME
Sep 22 13:15:30 core postfix/smtp[169236]: host smtp.zeptomail.com[165.173.183.10] offers SMTPUTF8 support, but not 8BITMIME
Sep 22 13:15:30 core postfix/smtp[169236]: 563E13FEC9: to=<1PHONE####@tmomail.net>, relay=smtp.zeptomail.com[165.173.183.10]:587, delay=0.91, delays=0.04/0/0.77/0.1, dsn=5.5.1, status=bounced (host smtp.
zeptomail.com[165.173.183.10] said: 530 5.5.1 Authentication Required. (in reply to MAIL FROM command))
Sep 22 13:15:30 core postfix/cleanup[169234]: 599173FED9: message-id=<20230922171530.599173FED9@core.HOST>
Sep 22 13:15:30 core postfix/bounce[169237]: 563E13FEC9: sender non-delivery notification: 599173FED9

Thank you for the help!

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