The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was '[email protected]'. Subject 'testing', Account: 'mail.eastern.com.ph', Server: 'smtp.eastern.com.ph', Protocol: SMTP, Server Response: '554 5.7.1 : Relay access denied', Port: 25, Secure(SSL): No, Server Error: 554, Error Number: 0x800CCC79

Greetings,
this is a server rejected recipient error message for Outlook/ outlook express. mainly if this is a correct email address that you were trying to send the email on then you need to check for the configuration settings for Outlook express.
Goto Outlook express- higlight mail tab- select the user a/c- click properties on right- goto server tab check that server is
incoming: pop3.eastern.com.ph
outgoing: smtp.eastern.com.ph
click save
Regards,
TechSup1