Exchange 2003 on a SBS server giving response "sorry, no mailbox here by that name (5.1.1 - chkuser)." to recipients when they're emailing valid emails within my domain

Hello,
      I installed exchange 2003 on this small business server about 4 months ago. After configuring it with the basics (forwarded ports, installed sp2 for exchange, setup imf, and verified business IP with a dns reverse showing the domain name to validate it to other mail servers that require the ptr) I still have one problem. The people who maintain and build our website use mozilla thunderbird as their email client. When they attempt to email known valid email addresses within my domain they get an error:

"An error occured while sending the mail. The mail server responded: sorry, no mailbox here by that name (5.1.1 - chkuser). Please verify that your email address is correct in your Mail preferences and try again."

Anyone know if it's their mail client or something with the exchange server that needs to be changed? I've never used thunderbird.

Thanks!
- Derrick
Dfoster05Asked:
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Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:
Well, since Thunderbird is not an Exchange client that would be the first problem... but are these folks inside the LAN?  How did they configure this to begin with?

I'll take a guess though, because you said they are your web designers...

They have most likely configured Thunderbird as a POP3 client to the mail server at wherever your web site is hosted... while this mail server is probably configured with your domain, it is not going to interact with your Exchange server, and is not authoritative for receiving messages so it will therefore not know that the address is a "valid email address within your domain".

I would also suspect that these folks do not have a mailbox configured in Exchange?  If they do, then they aren't accessing it with THunderbird.  If you want to provide them with an email address/mailbox, then they either need to use Outlook, or they should access their email via Outlook Web Access.

Jeff
TechSoEasy
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Dfoster05Author Commented:
Oops, Sorry! I kinda left that question open on parts and didn't explain enough. The web designers are not part of our organization. They were contracted to build the website for the business and are paid monthly upkeep on it for changes. The only thing they control is updates to our website, and they own the registrar information for our website's domain. They use their own mail server, which, I'm not sure what it is, but probably a pop3 of some kind.

Alright, so the only reason I mentioned thunderbird was the fact that I got a screenshot from one of the web designers (she sent it to a different address of mine of course) that showed the error I stated in the original problem coming up it's own error window (prompt box with info, an OK button.) Now, I know chkuser is part of several email servers out there... so I'm just wondering if it's something I need to configure in my exchange server to fix the problem. I'm just assuming Exchange has the user check turned off so people can't scan the server for valid emails (spam generators and the like;) however, either the server or the email client our web designers are using requires a chkuser to be successful before it'll event attempt to send the mail.

Anyone have any ideas?
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Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:
A chkuser error is not specific enough to know the answer to your question.  If you can please post the screenshot to:
https://filedb.experts-exchange.com/incoming/ee-stuff/258-IBCEmailH.jpghttps://filedb.experts-exchange.com/incoming/ee-stuff/251-holding.txt
 then perhaps it will make more sense.

Jeff
TechSoEasy
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Dfoster05Author Commented:
Jeff, I went ahead and attached the picture awhile back, didn't know it wouldn't notify you. Gotta forgive me for still being an EE newb sometimes!

As far as the issue goes it's still going on. We've been using some spare bellsouth accounts to communicate with the website people and that's been working. I did set up thunderbird on my laptop and attached it to my personal website's domain and sent mail to the client's office successfully over that. It's definately an issue with the web designer's email domain that they're not willing to even look into for me. Any help at this point would be appreciated even if it's just a conjecture of what could possibly be the issue. I have my idea but let me hear any comments opinions and I'll award points based on that.

Thanks for your help, as always
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Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:
Yeah... it doesn't... and once I post back to a question, it drops off of my queue, so only your posting back brought it back to my attention.  :-)

I would still think that my initial explanation is what's going on here... if your web designers are hosting YOUR website on the same server as THEIR website, then they won't be able to get beyond that server to send an email to your domain.  If you want to prove this theory you need to have access to your web server's control panel and set up an email account on the web server with someone@yourdomain.com.  Then have them send to someone@yourdomain.com and see the message not bounce, but rather go into that new email account.

But if they don't care, then too bad for them.

Jeff
TechSoEasy
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