granite03
asked on
Diagnostic-Code: smtp;550 sorry, no mailbox here by that name. (#5.7.17)
(SBS2003 Domain w/ Exchange Server 2003 SP2 - Firewall is a SonicWALL TZ170 - Pipex Web Fusion as DNS Host - Physical connection provided by NTL/Telewest/Virgin Media)
Intermittently now, people who attempt to email us from the internet are getting a bounce message back;
"Diagnostic-Code: smtp;550 sorry, no mailbox here by that name. (#5.7.17)"
Now, the mailbox DOES exist. There is no obvious problem with the Exchange Server, and we've run the Best Practices Analyzer.
There is a possible problem with the DNS Hosting company. DNSStuff said MX was unobtainable at one point, (low port test) in which case the only other IP in the DNS record is the A record (website), so is the  mail occasionally being directed there?
The only other possible problem I can think of is the fact that our internal Windows domain name is the same as the external domain name, and I know for a fact that this has caused email problems on other sites before. What I need is proof-positive, or advice either way.
I'm desperately trying to get hold of an intact 'bounce' message, as an attachment, rather than a forward but my users have not been too forthcoming on that score yet, mainly because of the difficulties involved in getting their clients to co-operate.
Client Mail--->their outbound SMTP server/smarthost--->DNS records--->MX--->Router WAN Port--->Port 25--->SBS Exchange Server--->User Mailbox
Can you guys fill in the missing jigsaw pieces in my reasoning?? Many thanks in advance.
Intermittently now, people who attempt to email us from the internet are getting a bounce message back;
"Diagnostic-Code: smtp;550 sorry, no mailbox here by that name. (#5.7.17)"
Now, the mailbox DOES exist. There is no obvious problem with the Exchange Server, and we've run the Best Practices Analyzer.
There is a possible problem with the DNS Hosting company. DNSStuff said MX was unobtainable at one point, (low port test) in which case the only other IP in the DNS record is the A record (website), so is the  mail occasionally being directed there?
The only other possible problem I can think of is the fact that our internal Windows domain name is the same as the external domain name, and I know for a fact that this has caused email problems on other sites before. What I need is proof-positive, or advice either way.
I'm desperately trying to get hold of an intact 'bounce' message, as an attachment, rather than a forward but my users have not been too forthcoming on that score yet, mainly because of the difficulties involved in getting their clients to co-operate.
Client Mail--->their outbound SMTP server/smarthost--->DNS records--->MX--->Router WAN Port--->Port 25--->SBS Exchange Server--->User Mailbox
Can you guys fill in the missing jigsaw pieces in my reasoning?? Many thanks in advance.
ASKER
The internal domain name (*********.com) is configured with the same name as the external DNS name (which points to their website and their router)
The problem is happening with several different mailboxes, so it's possibly all of them.
There are many different people who have tried to email in and received the bounce errors, but then get the mail through next time they try (which suggests DNS errors to me)
The problem is happening with several different mailboxes, so it's possibly all of them.
There are many different people who have tried to email in and received the bounce errors, but then get the mail through next time they try (which suggests DNS errors to me)
ASKER CERTIFIED SOLUTION
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ASKER
Well, they have no internal MX. They're a SME, with a managed connection, which forwards to a SonicWALL TZ170. From there, there's a port forward-all setup, which points to the IP of their Windows SBS. I may be showing up my lack of in-depth knowledge here, but it seems as if no internal MX is required!?
Other than that, I'm going to have one final stab at getting the ISP to take this seriously, then if that fails, move to a new ISP.
Other than that, I'm going to have one final stab at getting the ISP to take this seriously, then if that fails, move to a new ISP.
SOLUTION
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do you have your internal domain configured as the external one. The problem is happening with all mailboxes or just with one? The problem is happening from everybody on Internet or just one?
As you say it can be a DNS problem, but servers does not resolve MX with the A pointer if MX is not resolved. It's possible the MX record of EXTERNAL domain in misconfigured.
Shack,