I have a machine with the follow specs.

Linux hermes.business.com 2.6.11-1.1369_FC4 #1 Thu Jun 2 22:55:56 EDT 2005
i686 i686 i386 GNU/Linux

pam-0.79-8
dovecot-0.99.14-4.fc4

No one is able to receive e-mails due to authentication failures and yesterday afternoon
they were able to.

I tried the following command directly from the server and got the following results:

[root@hermes log]# telnet localhost 110
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
+OK dovecot ready.
USER user1
+OK
PASS ****************
-ERR Authentication failed.

I checked the /var/log/messages file and saw the following:

Jan 12 11:25:41 hermes unix_chkpwd[4601]: check pass; user unknown
Jan 12 11:25:41 hermes dovecot(pam_unix)[4600]: authentication failure; logname=
uid=0 euid=0 tty= ruser= rhost=  user=[user2]
Jan 12 11:33:50 hermes unix_chkpwd[4718]: check pass; user unknown
Jan 12 11:33:50 hermes dovecot(pam_unix)[4717]: authentication failure; logname=
uid=0 euid=0 tty= ruser= rhost=  user=[user1]

Here is my /etc/pam.d/dovecot file

#%PAM-1.0
auth       required     pam_nologin.so
auth       required     pam_stack.so service=system-auth
account    required     pam_stack.so service=system-auth
session    required     pam_stack.so service=system-auth

Any suggestions where to look to resolve the authentication issue?

Thanks,

David Kolts