Sending with Postfix: connection refused

I've just setup a mail server in Centos 5.5 following these guides:

wiki . centos . org/ HowTos/ postfix
wiki . centos . org/ HowTos/ postfix_sasl

The server is running on a static IP provided by my ISP, who also created a reverse DNS entry for me.

I can recieve mail and send mail to myself, however if I try to send to other domains my connection is refused. I've tried my ISP (who use pos tini filte ring) g ma il and h ot mail.

Some log entries:

Jun 25 15:31:30 slotin postfix/smtp18731: 6204240062: to=my_emailATmy_isp, relay=none, delay=0_44, delays=0_16/0_01/0_28/0, dsn=4_4_1, status=deferred (connect to my_isp_mail8_psmtp_com64_18_5_14: Connection refused)

Note: I had to strip out anything url-like, or spam 15 superfluous posts to get the logs on here, so pretend those underscores are periods and all the proper square brackets and greater than or less than are in there.

I don't think it's a firewall thing because if I telnet directly to my ISP's mail server it works fine.

# telnet mail.my.isp 25
Trying *.*.*.*...
Connected to mail.my.isp (*.*.*.*).
Escape character is '^]'.
220 mailout2.my.isp ESMTP Postfix

I did try with my firewall off, but just in case here are my rules:

Code:

---

# iptables -L
Chain INPUT (policy DROP)
target    prot opt source              destination
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:ssh
ACCEPT    icmp --  anywhere            anywhere            icmp echo-request
ACCEPT    icmp --  anywhere            anywhere            icmp type 30
ACCEPT    all  --  anywhere            anywhere
ACCEPT    all  --  anywhere            anywhere            state RELATED,ESTABLISHED
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:http
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:https
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:imap
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:imaps
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:pop3
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:pop3s
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:smtp
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:smtps
ACCEPT    tcp  --  anywhere            anywhere            tcp dpt:submission

Chain FORWARD (policy DROP)
target    prot opt source              destination

Chain OUTPUT (policy ACCEPT)
target    prot opt source              destination

Chain RH-Firewall-1-INPUT (0 references)
target    prot opt source              destination

---

It fixed itself, probably had to propegate the reverse DNS.