4.27 Mail sent to LISTSERV bounces with an Exchange error saying "user unknown"
We run LISTSERV on a machine called LISTSERV.EXAMPLE.COM. But when we send mail to that machine we always get an error back that looks like this:
Your message did not reach some or all of the intended recipients.
Sent: 4/10/2000 4:28 PM
The following recipient(s) could not be reached:
firstname.lastname@example.org on 4/10/2000 4:28 PM
The recipient name is not recognized
The MTS-ID of the original message is: c=US;a= ;p=ExampleCom
MSEXCH:IMS:ExampleCom International:POUGHKEEPSIE:NTSERVER 3550
(000B099C) 550 No such local user
We run Microsoft Exchange as our main mail gateway.
Exchange has an unfortunate habit of assuming that if it is supposed to handle mail for (say) example.com then it is also supposed to handle mail for all subdomains of example.com. Therefore if a piece of mail addressed to email@example.com passes through the Exchange machine, Exchange will attempt to handle that mail itself (presumably by looking for a local 'listserv' account) rather than (correctly) passing it off to listserv.example.com.
Since LISTSERV handles its own incoming mail, this means that mail addressed to the LISTSERV machine which passes through the Exchange server never gets to LISTSERV. Instead it typically gets bounced back to the sender with the error you reported.
The solution is to tell Exchange to hand off any mail sent to the listserv.example.com domain to the LISTSERV machine. We have some instructions provided to us by a customer for dealing with this sort of situation; note that since we don't use Exchange in-house we can't guarantee the accuracy of the instructions and if you have problems with them we will probably not be able to assist you further with your Exchange setup. Here are the instructions--use at your own risk:
| Open Exchange Administrator and navigate to your site's Connections
| container. Open the Internet Mail Service. Click on the Connections tab.
| Click on the E-Mail Domain button. Click on Add. In the EMail Domain box
| enter the FQDN for your LISTSERV computer (e.g. listserv.example.com).
| Check the Forward all messages for this domain to host: button and enter
| the IP address of the machine on which LISTSERV is installed -- this only
| works by IP address. Click on OK. OK. OK. OK. Stop and restart the
| Microsoft Exchange Internet Mail Service. And that should be it.
Again, if this fix does not work for you, you will have to consult the Exchange documentation or contact Microsoft support to resolve the problem. L-Soft does not run Exchange and does not support Exchange.