SMTP error: Can't relay email through server

I am trying to send a test email through the template preview and I am receiving an error message stating that my mailbox "is currently not 550 permitted to relay through this server." I have a shared hosting account .. do I need to contact the host directly? Will the WP SMTP plug-in help in this instance?

In the settings, this message appears several times: "Note: for SMTP method - in "From email" you should use only emails which related with your SMTP server!" What does that mean, "related"? Just simply that it is one of the actual email accounts for this domain?