[Dovecot] dovecot dead

[Allen Sim]

Hi,
I am a new linux user.I jz setting up a mail server.Downloaded &
Configured the components:CentOS,OpenLDAP,pam,dovecotMailServer,s
endmial,squireelmail etc....
But wehn i want to check whether it works or not, so i open up my
clientmail, wchi is Netscape 7.2. in Edit > Mail & Newsgroups Account
Setting > server setting... i had put the ip address for the
machine... but error pop out: Could not connect to mail server
10.XX.XX.XXX;the connection was refused. what's wrong wth it???

how to check wthere the mail server work?

my second question.
Dovecot dead but subsys locked

aft i typed: /etc/init.d/dovecot status,
it shows:dovecot dead but subsys locked.
I deleted /var/lock/subsys/dovecot. but whn i start my
dovecot,etc/init.d/dovecot start, same problem occur again....how to
solve ths???
below is frm /var/log/maillog :
Mar 19 15:17:28 hosting sendmail[3617]: m2J1EtMP003319:
to=<root at localhost.localdomain>, ctladdr=<root at localhost.localdomain>
(0/0), delay=06:02:32, xdelay=00:00:00, mailer=local, pri=665894,
dsn=4.0.0, stat=Deferred: local mailer (/usr/libexec/dovecot/deliver)
exited with EX_TEMPFAIL

i am new in this. anyone can help??? appreciate ur reply....