Problem relaying mail with smtp auth (sasl)

[mele...@gmail.com]

Hi,

I have a new ISP, and I'm having problems relaying all my email
through their SMTP server. My new ISP is lvcoxmail.com (Cox Business
Internet). I have SASL compiled in to my Postfix build (I use SASL to
authenticate relaying senders). I keep getting the SMTP error 421:
Sorry, you must log in before using this server.

In /etc/postfix/sasl_passwd I have my username/password (I have also
hashed this file, using postmap hash:/etc/postfix/sasl_passwd):

smtp.lvcoxmail.com<tab>username:password

Can anyone tell me what I'm doing wrong here? Thanks

Here is an output of my postconf -n (Sorry about the formatting, I'm
posting at google groups; also note, I have editted the mydomain and
myhostname variables just for the sake of anonymity):

root@XXXX:/etc/postfix# postconf -n
address_verify_map = btree:/var/spool/postfix/verified_senders
alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
body_checks = regexp:/etc/postfix/body_checks
command_directory = /usr/sbin
config_directory = /etc/postfix
content_filter = smtp-amavis:[127.0.0.1]:10024
daemon_directory = /usr/libexec/postfix
debug_peer_level = 2
disable_vrfy_command = yes
header_checks = regexp:/etc/postfix/header_checks
html_directory = /etc/postfix/README/HTML
inet_interfaces = $myhostname, localhost
mail_owner = postfix
mailbox_size_limit = 0
mailq_path = /usr/bin/mailq
manpage_directory = /usr/man
message_size_limit = 100000000
mime_header_checks = pcre:/etc/postfix/maps/mime_header_checks
mydestination = $myhostname, localhost.$mydomain, localhost,
$mydomain, mail.$mydomain, www.$mydomain, ftp.$mydomain
mydomain = example.com
myhostname = XXXX.XXXX.XXXX
mynetworks = 192.168.0.0/24, 127.0.0.0/8
mynetworks_style = subnet
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases
notify_classes = delay, resource, software
queue_directory = /var/spool/postfix
readme_directory = /etc/postfix/README
relayhost = smtp.lvcoxmail.com
sample_directory = /etc/postfix
sendmail_path = /usr/sbin/sendmail
setgid_group = postdrop
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options =
smtpd_banner = $myhostname ESMTP $mail_name
smtpd_data_restrictions = reject_multi_recipient_bounce
smtpd_helo_required = yes
smtpd_recipient_restrictions = reject_non_fqdn_recipient
reject_unknown_sender_domain reject_unknown_recipient_domain
permit_mynetworks permit_sasl_authenticated
reject_unauth_destination reject_invalid_helo_hostname
check_helo_access pcre:/etc/postfix/helo_checks check_sender_mx_access
cidr:/etc/postfix/bogus_mx reject_rbl_client
bl.spamcop.net reject_rbl_client zen.spamhaus.org
reject_rbl_client dsn.rfc-ignorant.org reject_rbl_client
list.dsbl.org reject_rbl_client dnsbl.njabl.org permit
smtpd_sasl_auth_enable = yes
strict_rfc821_envelopes = yes
unknown_local_recipient_reject_code = 550
virtual_alias_domains = hash:/etc/postfix/virtual_alias_domains
virtual_alias_maps = hash:/etc/postfix/virtual_alias_maps

[mele...@gmail.com]

Interesting, after a little more messing around with this setup, I
found that the server smtp.lvcoxmail.com requires pop-before-smtp.

Not what I would think would be a good setup for a relay server. Is
there a way to use this server as a relay from Postfix, or is the POP-
before-SMTP going to be too much to deal with from just Postfix?

Thanks