sorry clarification.. its not certain emails that i cant send as im attempting just to send an email with "test" in sub and "test" in message body its the email addresses i cant send to im getting error message 550 (email address is invalid) yet its a valid email that i get emails from this person yet when i attempt to reply i get email address is invalid...

this is a joke considering its a friend of mine i have confirmed the email address is correct and he sends me mail from the email (which i can open no problems) that im being told is invalid and dosent exist