returned email with 550 5.1.2 error

Posted on 2003-11-19
Medium Priority
Last Modified: 2008-02-01
Whenever I send email to my dad's office (only my dad's office, this doesn't happen for any other address i send mail to) my email gets bounced back with:

   ----- The following addresses had permanent fatal errors -----

   ----- Transcript of session follows -----
550 5.1.2 <dadsname@company.net>... Host unknown (Name server: companysmtp. company.net.: host not found)

This happens when I use two different POP3 email accounts with Outlook Express, AND when I use a Yahoo! account with my name.  However, it does not happen when I use a Yahoo account with a different name.  So, did my dad's office's antispam software suddenly start identifying my name as a spammer, and then refuse to deliver my email?

I've read that it could be becuase my ISP is associated with a spammer, but that's impossible becuase my ISP is provided by my university.

The ONLY reason I may suddenly by identified as a spammer is I wanted to see how "bouncing" worked, so I "bounced" a spam back to the sender of the spam.......would that somehow make my email account look like a spammer too?

How can I fix this?
Question by:kathena
LVL 44

Expert Comment

ID: 9784703
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What do these bounce messages mean?
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Accepted Solution

CrazyOne earned 1000 total points
ID: 9784708
Host Unknown
   ----- The following addresses had permanent fatal errors -----

   ----- Transcript of session follows -----
550 5.1.2 <JDOE@SWITCHGRASS.NET>... Host unknown (Name server:
mail.switchgrass.net.: host not found)

This means that our mail server was not able to locate the mail server for switchgrass.net (mail.switchgrass.net) in the Internet's domain name service (DNS). If the target system can't be found in the DNS, then our mail server can't connect to the remote mail server to deliver your message.

Most "host unknown" errors are caused by a typo in the domain name part of the intended recipient's address, but an increasing number of "host unknown" errors are the result of trying to reply to junk mail (spam). This is because the "From:" address on junk mail is almost always bogus. Where the address is typed correctly and is a real one, the problem is usually a temporary failure in DNS.

What you should do:
Confirm the intended recipient's address, if possible. Resend your message to the corrected address.

Author Comment

ID: 9784748
Unfortunately it is not that simple.  

There is no way the address is wrong, my dad will send me an email and i'll try to reply to it and it is rejected.

He can receive mail from other people, so his settings are not wrong, and I can send mail to other people so my settings are not wrong either.
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Expert Comment

ID: 11931938
I am suffering a similar, if not the same, situation. I can send to but cannot receive from a single address. The sendor has a second address that works fine. We cannot locate the difference in settings for the two of them.

Expert Comment

ID: 12053285
I am having the same problem. I am sending an email from an account on the same domain as the recipient, and it bounces back with the error. An NSLOOKUP for the domain, resolves to the proper address, so I assume the DNS is working properly. I've tried sending to other recipients (different domains) that are on the same server (same IP) and they are delivered fine. It appears that I only receive the error when the recipient's address is on the same domain.

Expert Comment

ID: 12053860
Down to senders machine! It initially appeared I could not receive email from a specific sender. I mistakenly assumed I could not receive from the domain of "canada.com". Since my earlier comment I have picked up 2 clients, both from the domain "canada.com". Both of those are flawless. We missed something when reviewing the senders configuration.

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