1. Fedora Core 5 perfect setup with ISPConfig.
2. main.cf exactly as shown in the howto in #1 no additions or changes.
3. Postifx has no problem relaying mail from other servers.
4. nmap shows port 25 open.
5. localhost telnet to port 25 works as expected and replies quickly.
6. External telnet, if it works, takes a long time to reply.
7. Sending mail from my mail client, if it works, takes a long time to process even a single mail.
8. When sending mail from my local client times out, sometimes there is no mention of anything in /var/log/maillog and sometimes there is:
Jan 30 09:18:57 MY_HOST postfix/smtpd: connect from MY_HOST.DOMAIN_NAME.net[127.0.0.1]
Jan 30 09:18:57 MY_HOST postfix/smtpd: lost connection after CONNECT from MY_HOST.DOMAIN_NAME.net[127.0.0.1]
Jan 30 09:18:57 MY_HOST postfix/smtpd: disconnect from MY_HOST.DOMAIN_NAME.net[127.0.0.1]
9. When sending mail from my client fails, the web site hosted from the server is still served quickly.
10. I don't know if has anything to do with the problem or not or if it is a different problem but when sending mail from my mail client does work, although slow, there is this in maillog :
Jan 30 09:03:17 MY_HOST postfix/smtpd: setting up TLS connection from MY_HOST.DOMAIN_NAME.net[127.0.0.1]
Jan 30 09:03:17 MY_HOST postfix/smtpd: TLS connection established from MY_HOST.DOMAIN_NAME.net[127.0.0.1]: TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)
Jan 30 09:03:17 MY_HOST sendmail: STARTTLS=client, relay=[127.0.0.1], version=TLSv1/SSLv3, verify=FAIL, cipher=DHE-RSA-AES256-SHA, bits=256/256
Jan 30 09:03:17 MY_HOST postfix/smtpd: 6B8111B7287: client=MY_HOST.DOMAIN_NAME.net[127.0.0.1], sasl_sender=web1_USER@MY_HOST.DOMAIN_NAME.net
11. I can connect with my mail client to receive email with no problems and receiving is fast.
12. It seems, although I am not sure, that it makes a difference where I am connecting from, i.e. work or home.
13. Although both connections, work and home are with different ISPs, they are both 100mbs fiber connections.
So, sending mail from my client works sometimes although slow, sometimes the connection times out with the server seeming to not see the connection at all and sometimes a connection is made but then dropped.
[EDIT] I should mention, sending and receiving using web-mail on the server is no problem at all so worst case scenario, I just don't use a mail client. ;-) [/EDIT]