[Sendmail] Sending mail fail with error 500 (Service unavailable)

Hi guys,

Have been trying to fix this for the past couple of hours and i'm all out of ideas.

Here is the setup:

We use google apps. and receive all out emails to *@mydomain.dk on googles servers, our mx records point there. But we have some servers, in this example "server.mydomain.dk" that is used to send-only (never receives) emails from *@mydomain.dk All SPF and PTR records are set up to support sending emails from this server on our domain.

No one has made any changes on the server, but it was restarted yesterday.

Here is what the log shows, when i try to send a mail from the server:

Jul 7 12:46:01 server sendmail[50150]: s67Ck1OM050150: from=root, size=22799, class=0, nrcpts=1, msgid=<201407071246.s67Ck1OM050150@server.mydomain.dk>, relay=root@localhost Jul 7 12:46:01 server sendmail[50151]: s67Ck1h4050151: from=<root@server.mydomain.dk>, size=23022, class=0, nrcpts=1, msgid=<201407071246.s67Ck1OM050150@server.mydomain.dk>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1] Jul 7 12:46:01 server sendmail[50150]: s67Ck1OM050150: to=useraccount@mydomain.dk, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=52799, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s67Ck1h4050151 Message accepted for delivery) Jul 7 12:46:01 server sendmail[50153]: STARTTLS=client, relay=aspmx.l.google.com., version=TLSv1/SSLv3, verify=FAIL, cipher=ECDHE-RSA-AES128-GCM-SHA256, bits=128/128 Jul 7 12:46:02 server sendmail[50153]: s67Ck1h4050151: to=<useraccount@mydomain.dk>, ctladdr=<root@server.mydomain.dk> (0/0), delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=143022, relay=aspmx.l.google.com. [IPv6:2a00:1450:4010:c04::1a], dsn=5.0.0, stat=Service unavailable Jul 7 12:46:02 server sendmail[50153]: s67Ck1h4050151: s67Ck2h4050153: DSN: Service unavailable Jul 7 12:46:03 server sendmail[50153]: STARTTLS=client, relay=aspmx.l.google.com., version=TLSv1/SSLv3, verify=FAIL, cipher=ECDHE-RSA-AES128-GCM-SHA256, bits=128/128 #at this point, the above mail failed and the next mail is a error report to the root mailbox Jul 7 12:46:03 server sendmail[50153]: s67Ck2h4050153: to=root@mydomain.dk, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=54256, relay=aspmx.l.google.com. [IPv6:2a00:1450:4010:c04::1a], dsn=5.0.0, stat=Service unavailable Jul 7 12:46:03 server sendmail[50153]: s67Ck2h4050153: s67Ck2h5050153: return to sender: Service unavailable Jul 7 12:46:03 server sendmail[50153]: STARTTLS=client, relay=aspmx.l.google.com., version=TLSv1/SSLv3, verify=FAIL, cipher=ECDHE-RSA-AES128-GCM-SHA256, bits=128/128 Jul 7 12:46:04 server sendmail[50153]: s67Ck2h5050153: to=root@mydomain.dk, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=55280, relay=aspmx.l.google.com. [IPv6:2a00:1450:4010:c04::1a], dsn=5.0.0, stat=Service unavailable Jul 7 12:46:04 server sendmail[50153]: s67Ck2h4050153: Losing ./qfs67Ck2h4050153: savemail panic Jul 7 12:46:04 server sendmail[50153]: s67Ck2h4050153: SYSERR(root): savemail: cannot save rejected email anywhere 

I should note, that i have had this problem before (also on this server) but it just suddenly worked by itself, so i assumed it was google that had a problem.

I have tried the following (in that order) and none of it has worked:

1. Restarting sendmail
2. Tested that sending email from another server to a adress on @mydomain.dk works (it did, so not google who has a problem)
3. Made sure everything was resolving correctly, it is. mx records are also correct.
4. commented out everything in /etc/resolv.conf and added only 8.8.8.8 as DNS server #at this point, all DNS has been tested, and i'm almost sure that it's not a DNS problem. Most google results tell me it's a DNS problem though..
5. recreated /etc/mail/access with external server DNS name and ip adress added.
6. Checked that the correct FQDN (server.mydomain.dk) was returned from "hostname" command

Can anyone tell me why this server can't send emails? or got any ideas? Then please leave a comment!

EDIT: Added some things that i tried/checked