I have fresh installed Debian 12 with Ispconfig 3.2.11P Almost everything work fine, except there is no IPv6 reachability mail server. When I do an online mail test with MXtools I get the error (see attachment) How can I solve this problem?
The error says the e-mail server can not be reached with IPv6 on port 25. Does the host have IPv6 address? Is it configured? Is there a firewall blocking access to port 25?
