I installed and configured successfully sendmail 8.12.9 on a RH 9 server. Now, i can send mails without a problem. But whenever I collect my incoming mail using any MUA or Outlook, the following appeared on my mail logs:

Nov 25 17:12:13 webmail pop(pam_unix)[4920]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=192.168.0.3 user=mailuser
Nov 25 17:12:15 webmail ipop3d[4920]: Login failed user=mailuser auth=mailuser host=ntserver.domain.com [192.168.0.3]
Nov 25 17:12:16 webmail ipop3d[4920]: Command stream end of file while reading line user=mailuserhost=ntserver.domain.com [192.168.0.3]
Nov 25 17:14:03 webmail ipop3d[4921]: Login failed user=mailuser#203.x.x..x auth=mailuser#203.x.x.x host=webmail.domain.com [192.168.0.4]
Nov 25 17:26:26 webmail ipop3d[4926]: Login failed user=mailuser#203.x.x.x auth=mailuser#203.x.x.x host=webmail.domain.com [192.168.0.4]
Nov 25 17:27:36 webmail last message repeated 2 times
Nov 25 17:27:41 webmail ipop3d[4926]: Login excessive login failures user=mailuser#203.x.x.x auth=mailuser#203.x.x.x host=webmail.domain.com [192.168.0.4]

I am sure that username and password inputed are precise. But still can't make that authentication successful.

My mail server has IMAP and POP3 running under xinetd.

Here's my /etc/pam.d/imap
#%PAM-1.0
auth required /lib/security/pam_stack.so service=system-auth
account required /lib/security/pam_stack.so service=system-auth


---the same entries for my POP3. And my /etc/xinetd.d/pop3

service pop3s
{
disable = no
socket_type = stream
wait = no
user = root
server = /usr/sbin/ipop3d
only_from = 0.0.0.0/0
no_access =
instances = 30
log_on_success += DURATION HOST
log_of_failure += HOST
nice = -2
}


for my /etc/xinetd.d/imap
service imap
{
disable = no
socket_type = stream
wait = no
protocol = tcp
flags = IPv4
user = root
server = /usr/sbin/imapd
only_from = 0.0.0.0/0
no_access =
instances = 30
log_type = FILE /var/log/xinetd.log
log_on_success += DURATION HOST
log_of_failure += HOST
nice = -2
bind = 127.0.0.1 192.168.0.4
}


My /etc/mail/sendmail.cf looks like this:
# SMTP daemon options
O DaemonPortOptions=Name=MTA
O DaemonPortOptions=Port=587, Name=MSA, M=E

# SMTP client options
#O ClientPortOptions=Family=inet, Address=0.0.0.0


Also, made the email user entries on my /etc/mail/aliases to correspond to my LAN clients.
I have a permission to relay messages to my ISP. And I also have a valid IP Address.
Also, there is no firewall running on my mail server.

But still having the problem.

Many thanks in advance.