Postfix can’t send mails

[thavaht]

I’ve set up a mail server following “The Perfect Setup - Debian Etch (Debian 4.0)” how-to and all worked fine until today.
From this morning I can no longer send mails to other domains but I can send them locally and I still receive mails from everywhere.
In my /var/log/mail.log, each time I try to send mails outside, I see messages like the following:

Jun 15 23:37:37 mail imapd: Connection, ip=[::ffff:127.0.0.1]
Jun 15 23:37:37 mail imapd: LOGIN, user=thavaht, ip=[::ffff:127.0.0.1], protocol=IMAP
Jun 15 23:37:37 mail imapd: LOGOUT, user=thavaht, ip=[::ffff:127.0.0.1], headers=1334, body=0, rcvd=311, sent=3424, time=0
Jun 15 23:37:59 mail postfix/smtp[5394]: 4EE961E1A8A: lost connection with gmail-smtp-in.l.google.com[64.233.183.27] while receiving the initial server greeting

I’ve walked around several Postfix articles and googled for this message all the day with no success. Need a help.

[falko]

Please check if your server is blacklisted: http://www.mxtoolbox.com/blacklists.aspx

[thavaht]

Thank you very much for helping.
In fact I found that my server is listed.
The blacklist names are:
FIVETENFREE, FIVETENIGNORE, FIVETENKLEZ, FIVETENMULTI, FIVETENOPTIN, FIVETENOTHER, FIVETENSINGLE, FIVETENSRC, FIVETENTCPA, FIVETENWEBFORM

The reason:
“miscellaneous address blocks that have sent spam here
Return codes were: 127.0.0.2”

Following your suggestion, I’ve checked other lists on other pages and the only reference I found is FIVETEN.
I wonder how I get out of it. Any help will be appreciated.

[falko]

You must make sure that your server isn't abused by spammers. If you are sure, contact the maintainers of the blacklist and ask them to remove your server from their blacklists.

[thavaht]

I sent a mail to blackhole18 at five-ten-sg.com and I’m happy to see that they removed my IP from the list. However I can’t send mails yet.
I checked again and found that the IP of my Provider’s proxy server is still listed there; so that’s a matter to deal with them.