Problem accessing PLUG domain from my home domain

Hello,

When I try to send mail from my home server to PLUG
list, it ends up in mail queue. So, I go to webmin
interface and try to flush the queue, it comes back as
following:

************************
Forcing the attempted delivery of mail with the
command /usr/lib/sendmail -v -q
-C/etc/mail/sendmail.cf ..

Running /var/spool/mqueue/h4JH4BAx014168 (sequence 1
of 1)
lists.PLUG.phoenix.az.us: Name server timeout
<plug-discuss@lists.PLUG.phoenix.az.us>... Transient
parse error -- message queued for future delivery
**************************

What's the problem? It used to work.

Sundar

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