A customer calls in with an e-mail issue. Mail flow is working internally, and has been validated already technically. The user is having trouble sending an e-mail to a particular user on a large e-mail hosting service like Yahoo or G-Mail. The SMTP bounceback error is an undeliverable 5.3.0. It looks like the mail server may be blacklisted. What are some troubleshooting steps you need to take to diagnose and resolve this issue?

Hi, First check the mx entries of the receiver part and try to connect telent in port 25. If that's not working, assume that the dns is not resolving correctly (Test it by change the dns server to a public dns like 8.8.8.8) If that's working fine, try to send email from command prompt. You may also check whether you have the valid ptr recor for your email domain (some of the email system willn't allow to deliver them email if the sender is not having proper ptr recor.) If everything is going fine, you may also contact them to check whether they have your name in balck list.Regards from www.windowsadmin.info | www.blog.windowsadmin.info

1) You can also check your domain blacklist by going to http://www.mxtoolbox.com/blacklists.aspx 2) When you tried to connect to yahoo via telnet, where did it fail and what error message did you get? From the commands, the list should go like this: 1: EHLO your.domain 2: MAIL FROM: you@your.domain 3: RCPT TO: you@your.yahoo.address 4: DATA 5: SUBJECT: put the subject here 6: Now, press enter 2 times. You won't see a response. 7: Now, type the subject 8: Put the period (.) on the blank line. 9: QUIT Letus know the results.Viral Rathod Blog : http://viralr.wordpress.com

Can we know what was the resolution ?Viral Rathod Blog : http://viralr.wordpress.com