How to fix SMTP error?

Question

PHP

THIS IS WHEN YANDEX MAIL:
Sorry! An error has occurred.
Unable to send e-mail.
Please contact the forum administrator with the following error message reported by the SMTP server: "553 5.7.1 Sender address rejected: not owned by auth user."
THIS IS WHEN MAIL MAIL:
Sorry! An error has occurred.
Unable to send e-mail.
Please contact the forum administrator with the following error message reported by the SMTP server: "501 Syntactically invalid EHLO argument(s)"