sendmail fails to recognize Internet host names

netstat -anp shows:
tcp        0      0 0.0.0.0:25                  0.0.0.0:*                   LISTEN      10016/sendmail: acc
tcp        0      0 0.0.0.0:110                 0.0.0.0:*                   LISTEN      9968/cyrus-master
tcp        0      0 0.0.0.0:143                 0.0.0.0:*                   LISTEN      9968/cyrus-master
udp        0      0 0.0.0.0:53                  0.0.0.0:*                               5148/named
udp        0      0 192.168.1.10:53            0.0.0.0:*                               5148/named
udp        0      0 127.0.0.1:53                0.0.0.0:*                               5148/named
tcp        0      0 :::110                      :::*                        LISTEN      9968/cyrus-master
tcp        0      0 :::143                      :::*                        LISTEN      9968/cyrus-master
so imaps is missing, can't start, presumably because of this:
Feb 26 16:29:46 orion imap[9986]: version conflict in sasl_client_add_plugin for gssapiv2
Feb 26 16:29:46 orion imap[9986]: version conflict in sasl_client_add_plugin for digestmd5
Feb 26 16:29:46 orion pop3[9989]: version mismatch on plugin
Feb 26 16:29:46 orion imap[9987]: version conflict in sasl_client_add_plugin for anonymous
Feb 26 16:29:46 orion imap[9986]: version conflict in sasl_client_add_plugin for anonymous
Feb 26 16:29:46 orion imap[9987]: version conflict in sasl_client_add_plugin for crammd5
Feb 26 16:29:46 orion imap[9986]: version conflict in sasl_client_add_plugin for crammd5
So this goes back to my earlier posting, which I deleted because there were no answers.

I can verify cyrus users on localhost, sasldblistusers works, and the sendmail and imapd certs are set to mail.mydomain.com.  

Are the version conflict errors blocking sendmail from authenticating mail.mydomain.com on the Internet?

 

Thanks!  Here goes:

$ telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to orion.mydomain.com (127.0.0.1).
Escape character is '^]'.
220 orion.mydomain.com ESMTP Sendmail 8.13.1/8.13.1; Tue, 27 Feb 2007 10:12:06 -0900
HELO localhost
250 orion.mydomain.com Hello orion.mydomain.com [127.0.0.1], pleased to meet you
MAIL FROM: user@mydomain.com
250 2.1.0 user@mydomain.com... Sender ok
RCPT TO: user@gmail.com
553 5.1.2 user@gmail.com... Unrecognized host name gmail.com.
DATA
503 5.0.0 Need RCPT (recipient)
QUIT
221 2.0.0 orion.mydomain.com closing connection
Connection closed by foreign host.
/var/log/maillog
Feb 27 10:12:14 orion sendmail[11021]: l1RJBnoU011021: user@gmail.com... Unrecognized host name gmail.com.
Feb 27 10:12:22 orion sendmail[11021]: l1RJBnoU011021: from=user@mydomain.com, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, relay=orion.mydomain.com [127.0.0.1]
Feb 27 10:12:57 orion sendmail[11023]: l1RJCW8S011023: user@gmail.com... Unrecognized host name gmail.com.
Feb 27 10:13:02 orion sendmail[11023]: l1RJCW8S011023: from=user@mydomain.com, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, relay=orion.mydomain.com [127.0.0.1]

$ nslookup -q=MX gmail.com
Server:         192.168.1.10
Address:        192.168.1.10#53

Non-authoritative answer:
gmail.com       mail exchanger = 50 gsmtp183.google.com.
gmail.com       mail exchanger = 5 gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 10 alt1.gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 10 alt2.gmail-smtp-in.l.google.com.
gmail.com       mail exchanger = 50 gsmtp163.google.com.

Authoritative answers can be found from:
gmail.com       nameserver = ns2.google.com.
gmail.com       nameserver = ns3.google.com.
gmail.com       nameserver = ns4.google.com.
gmail.com       nameserver = ns1.google.com.

Thanks anfi, I've read about that - sendmail.mc contains a similar line:
MAILER(smtp)dnl
I had already attempted to change the syntax to correspond to your suggestion and that made no difference, so I restored the original setting.  
These comments have been helpful however in narrowing down the problem!  I finally recalled that after install, I couldn't find BIND so I installed DNS, which led me to believe that sendmail simply didn't recognize that DNS was installed.  So I uninstalled sendmail rpms with their dependencies and reinstalled them, and the "unrecognized host name" error disappeared :)  

I would be happy enough to close this ticket, but one nagging problem remains: only a telnet connection from localhost or orion.mydomain.com actually connects to the remote host without error.  If I use the address mail.mydomain.com, I get this error
with RCPT TO: user@yahoo.com
550 5.7.1 user@yahoo.com... Relaying denied.  IP name possibly forged [192.168.1.10]
but with MAIL FROM: user@yahoo.com
250 2.1.0 user@yahoo.com... Sender ok
Why does sendmail give me a "Relay denied" error for mail to the Internet, but not for mail from the Internet?  
Similarly, pop3 mail clients on my non-routed network and on my routed /29 network cannot send mail. The mail client errors differ, but the server error in my mail log reads as above (Relaying denied, IP name possibly forged), followed by this: [client] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA.  However my caching name server was able to send mail to the Internet through an Evolution client without error. So what could be the problem?

Have you  generated new sendmail.cf from sendmail.mc with MAILER(`smtp')?
Have you restarted sendmail daemon (or HUPed it) after changing sendmail.cf?

Thanks dalesit, that was a good recap on the access file!  I did have a subnet declaration, but was stumped by the syntax.  I used 192.168.1.0, with no subnet mask declaration because I hadn't seen any in other examples.  I suppose that sendmail doesn't recognize 4 octets as a subnet, since there's no place for a mask, but it's confusing nonetheless.

Now I just need to get my mail client to send mail (it fails on "no credentials cache found"
which may relate to an lmptunix duplicate check error in the mail log, but for now all I get is the usual "did not issue MAIL/EXPN/VRFY/ETRN").  Anyway, I have to break these questions up somewhere, and this one could take some time.