[Dovecot] can't connect to smtp, or login to imap, pop3

[dtra-fyf]

hi all

i'm using fedora core 4, with postfix and dovecot (0.99) installed via yum

i can send mail from the server (using mail), and i can receive mail in 
my user mailbox on the server

but i can't send email using a client like thunderbird (it won't connect 
to the smtp server)

and i can't download email from pop3 using thunderbird
it always says authentication failed when i try to login

using squirrelmail, it always says username and password incorrect

but i know for sure the username and password are correct

dovecot conf file is as folows

-------imap_listen = [::]
-------pop3_listen = [::]

-------imaps_listen = [::]
-------pop3s_listen = [::]
-------ssl_cert_file = /etc/pki/dovecot/dovecot.pem
-------ssl_key_file = /etc/pki/dovecot/private/dovecot.pem
-------mbox_locks = fcntl
-------auth = default
-------auth_mechanisms = plain
-------auth_userdb = passwd
-------auth_passdb = pam

-------# i've tried with and without the next line, with no effect
-------user = dovecot

everything else is commented out

this is the log file for dovecot
-------dovecot: Apr 14 23:34:35 Info: Dovecot starting up
-------pop3-login: Apr 14 23:34:52 Info: Disconnected 
[::ffff:###.##.###.###]
-------imap-login: Apr 14 23:35:09 Info: Aborted login [::ffff:127.0.0.1]


my iptables are as follows

-------*filter
-------:FORWARD ACCEPT [0:0]
-------:INPUT ACCEPT [0:0]
-------:OUTPUT ACCEPT [0:0]
--------A INPUT -p tcp -m tcp --dport 993 -j ACCEPT
--------A INPUT -p tcp -m tcp --dport 110 -j ACCEPT
--------A INPUT -p tcp -m tcp --dport 25 -j ACCEPT
--------A INPUT -p tcp -m tcp --dport 143 -j ACCEPT

--------A INPUT -i lo -j ACCEPT

let me know, and i'll see if i can post the postfix conf/log file as well


any ideas?
thanks
dave