Question : Getting NDR 3030 Errors for all emails sent to One specific Mail Domain mail.charter.net - SMTP unable to authenticate

Hello,

This has been killing me.  I am not listed as a spam relay on dnsstuff.com.  I don't show any DNS issues as I can ping and resolve mail.charter.net.  I do not get NDR errors for any other domain.  I can send email no problem to anyone on the charter.net domain from my yahoo account.  My queue is stuck on retry for charter.net and when I try to authenticate to it using telnet mail.charter.net 25, I get the correct prompt.  

Our office is on Exchange 2003 with SBS 2003.  I have read the articles Q_21190821 and a few others on expert-exchange but can't seem to get anywere with this problem.  Can anyone tell me how to make the authentication with this mail domain work again?

Thank you so much in advance for any help I can get.

Answer : Getting NDR 3030 Errors for all emails sent to One specific Mail Domain mail.charter.net - SMTP unable to authenticate

Can you try and send the mail directly to the mail server using telnet.

here is how, just open command prompt and type just like this.

telnet mail.charter.net 25
helo localdomainname.com
mail from:your_email_id@localdomainname.com
rcpt to:receipent_username@charter.net
data
subject:Test mail
test mail
.

Put the dot in last line.

This should give you message that your mail has been queued for delivery.

Could you try this.