Failed MX lookup on tcp_intranet
Hi, I have a new test installation of Comms Suite 5:
Sun Java(tm) System Messaging Server 6.3-0.15 (built Feb 9 2007)
libimta.so 6.3-0.15 (built 19:27:56, Feb 9 2007)
SunOS uwc 5.10 Generic_118833-36 sun4v sparc SUNW,Sun-Fire-T1000
This is a two-tiered deployment. If I enable Messenger Express on the message store system, I can send and receive mail within this test domain. But when I send mail with either Messenger Express or Communications Express on the front-end, it sits in the tcp_intranet queue with the following message in mail.log_current:
24-May-2007 21:18:08.79 tcp_intranet Q 1 testuser@mydomain.com rfc822;testuser@mydomain.com @store.mydomain.com:testuser@mydomain.com Failed MX lookup; try again later
This all makes sense to me: This is a user in this domain, on the system store.mydomain.com. I don't understand why it is attempting a DNS lookup. The store system is reachable as both "store.mydomain.com" and "store" using entries in /etc/hosts. It is correct that DNS is not configured on this system, it just seems odd to me that DNS is necessary on the tcp_intranet channel.
Can anyone shed some light?
Thanks.
[1192 byte] By [
esb2000a] at [2007-11-27 5:27:05]
# 1
Hi,
> This is a two-tiered deployment. If I enable
> Messenger Express on the message store system, I can
> send and receive mail within this test domain. But
> when I send mail with either Messenger Express or
> Communications Express on the front-end, it sits in
> the tcp_intranet queue with the following message in
> mail.log_current:
>
> 24-May-2007 21:18:08.79 tcp_intranet Q 1
> testuser@mydomain.com rfc822;testuser@mydomain.com
> @store.mydomain.com:testuser@mydomain.com Failed MX
> lookup; try again later
>
> This all makes sense to me: This is a user in this
> domain, on the system store.mydomain.com. I don't
> understand why it is attempting a DNS lookup. The
> store system is reachable as both
> "store.mydomain.com" and "store" using entries in
> /etc/hosts. It is correct that DNS is not configured
> on this system, it just seems odd to me that DNS is
> necessary on the tcp_intranet channel.
DNS is fundamental to the delivery of email. By default tcp_intranet channel has the 'mx' keyword which means it will try an MX lookup for the outgoing host/domain.
You can prevent this by changing the 'mx' to 'nomx' on the tcp_intranet channel definition in the imta.cnf file so it will deliver to the A record of the domain instead.
Run ./imsimta cnbuild;./imsimta restart for the change to take affect.
Regards,
Shane.
# 2
> Hi,
>
> > This is a two-tiered deployment. If I enable
> > Messenger Express on the message store system, I
> can
> > send and receive mail within this test domain.
> But
> when I send mail with either Messenger Express or
> Communications Express on the front-end, it sits in
> the tcp_intranet queue with the following message
> in
> mail.log_current:
>
> 24-May-2007 21:18:08.79 tcp_intranet Q
> 1
> testuser@mydomain.com rfc822;testuser@mydomain.com
> @store.mydomain.com:testuser@mydomain.com Failed MX
> lookup; try again later
>
> This all makes sense to me: This is a user in this
> domain, on the system store.mydomain.com. I don't
> understand why it is attempting a DNS lookup. The
> store system is reachable as both
> "store.mydomain.com" and "store" using entries in
> /etc/hosts. It is correct that DNS is not
> configured
> on this system, it just seems odd to me that DNS is
> necessary on the tcp_intranet channel.
>
> DNS is fundamental to the delivery of email. By
> default tcp_intranet channel has the 'mx' keyword
> which means it will try an MX lookup for the outgoing
> host/domain.
>
> You can prevent this by changing the 'mx' to 'nomx'
> on the tcp_intranet channel definition in the
> imta.cnf file so it will deliver to the A record of
> the domain instead.
>
> Run ./imsimta cnbuild;./imsimta restart for the
> change to take affect.
>
> Regards,
>
> Shane.
Shane, thanks for your reply.
This is still a little confusing. I can set up DNS, but if this MTA looks up the MX record for the domain, it will get its own address. This MTA is the front-end, it is trying to deliver to the message store. I completely understand the need for DNS and the MX lookup on tcp_local, but I'm not clear about what the MTA will do with the information it receives in the MX record.
Thanks.
# 3
Hi,
> This is still a little confusing. I can set up DNS,
> but if this MTA looks up the MX record for the
> domain, it will get its own address.
Actually this depends on how you configure your DNS. By default most people only create A records, if a host doesn't have an MX record then it falls back to using the A record instead.
But this isn't the case for you. When messaging server attempted to resolve the MX record it could not (as opposed to looking up the record and getting a null/empty result):
> testuser@mydomain.com rfc822;testuser@mydomain.com
> @store.mydomain.com:testuser@mydomain.com Failed MX
> lookup; try again later
You either need to work out why your system cannot resolve MX records for the hostname or just get messaging server to use the A record by default (which I hope it _can_ resolve).
Basically there are DNS resolution issues with your system, the option I provided works around this issue.
Regards,
Shane.
