Hi I would like to know what happen when Exchange 2003 receive a wrong alias email adr?For exemple:User: John TestPrimarySMTP: john.test@enterp.comsec SMTP: john.test@enter.caIf someone by mistake send an email to john.text@enter.ca instead john.test@enter.ca, what happen?1- Does it create a loop until the maximum hop count was exceeded for this message?2- Is there an err msg will be sent?Thank you.

Hi, The mail will not go into loop. Exchange will try to look for the address John.text@enter.ca and if not found then it will bounce back to the sender with Invalid Recipient NDR. Thanks. Vishal Ramnani | MCITP - Exchange 2007 | MCSE Messaging | MCTS - Win 2008 Config

It will bounce back with NDR "Mailbox doesnot exist" How to Understand an Exchange Non Delivery Report (NDR) http://www.petri.co.il/understanding-explaining-exchange-non-delivery-report-ndr.htmVinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

I ask you that question because I see the msg keep switchingbetween Exchange and SMTP server till it exceeded maximum hop count. Is it normal?: Event Type: Error Event Source: MSExchangeTransport Event Category: NDR Event ID: 3005 Date: 11/25/2009 Time: 5:34:19 PM User: N/A Computer: EXCHANGE01 Description: A non-delivery report with a status code of 4.4.6 was generated for recipient rfc822; john.text@enter.ca (Message-ID <...>). Cause: The maximum hop count was exceeded for this message. This non-delivery report can also be caused if a looping condition exists between sending and receiving servers that are not in the same Exchange organization. In this situation, the message bounces back and forth until the hop count is exceeded. A configuration error in the e-mail system can also cause the message to bounce between two servers or to be forwarded between two recipients. Solution: The maximum hop count is a property set on each virtual server and you can manually override it. The default maximum hop count is 15. Also, check for any situations that might cause loops between servers.

So it is looping?That tells me the the SMTP server ( Whatever that is), is misconfigured somehow.Message tracking should give you a better idea whats going on in that case.

Ya but the prob is always happen on the domain "enter.ca" which is not our main domain (enterp.com). It seems Exchange says: my main domain is "enterp.com" so I don't have email adr john.text@enter.ca so I will sent it to SMTP server and on SMTPserver the domain "enter.ca" it pointed to Exchange server. So the prob is it on Exchange config for extra domain? Instead to send it back again to SMTP server, should it just send an err msg?

Why does the SMTP server think Exchange is authorative for enter.ca if its not? I would check the configuration, rules, DNS etc..on the SMTP server.

Hi Andy,It more complicated than that. The SMTP server is also a mail filter and depending on domain of the recipients the emails are redirect to different mail servers...Basically, my question as soon Exchange get a wrong email adr does itsend immediately an err msg to the sender?

If you have recipient filtering enabled against users in Active Directory, then a message sent to an invalid recipient will never be accepted by the Exchange server and the sending server is responsible for generating the NDR to the sender.If you do not have recpient filtering enabled, then Exchange will accept the message and then generate the NDR.Either way, it should happen rather quickly, yes.

What happen when an email is looping like in my case? Is there a way to know the details of the transactions for each time the email is sent or received during that looping moment?

This is where I would check the SMTP logs on both the Exchange Server and your SMTP gateway.If necessary, enable SMTP protocol logging for Exchange.http://support.microsoft.com/kb/821910It still sounds like the culprit is the SMTP gateway.

Ok I have checked on SMTP logs and it seems SMTP keep receiving the same email from Exchange...for exemple:1-kim@bona.ca sent to john.test@enter.ca(which is not existed)2- The SMTP server receive the email and send it to Exchange3- Because the email does not existed then Exchange sent an email back to STMP server but with:from = kim@bona.ca to = john.test@enter.ca4-So the same process keep repeatinguntil it exceeds maximum hop count.How is that possible?

Ok I got the solution...I had just need to add that domain as an smtp which is managed by thedefault policy of Exchange.

But I thought that wasnt a domain you were authorative for?