Why am I getting error ''550 This mail is not local'' when trying send mail through my mail server?

This happens because our mail server treats the message you are sending as SPAM.

The message is considered to be SPAM if:

-'FROM' field is missing in the email message
-Neither 'FROM' nor 'TO' field contains an existing e-mail address on your mailserver.
-Your SMTP session is not being authenticated.

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