Today i found out that on one of my servers, i can not establish a connection via IMAP.
The portscanner within the ISPConfig (on the server itself), shows that the following IMAP ports are open:
Port 143 (tcp) is open (imap2)!
Port 993 (tcp) is open (imaps)!
netstat -tap | grep imap shows me:
tcp6 0 0 *:imaps *:* LISTEN 1980/couriertcpd
tcp6 0 0 *:imap2 *:* LISTEN 1968/couriertcpd
But when i try to establish a connection via telnet from my local desktop with:
telnet 18.104.22.1689 143
The firewall on port 143 within ISPConfig is disabled.
Within Outlook Express i receive the error code: 800ccc0e
This means that a connection is not possible.
My conclusion is that i can not establish a connection via port 143 from outsite the mailserver.
Any suggestions to solve this problem?