Problem with SMTP port

[Progenic]

I scanned my ports after i installed the mail server. All port were running, but the SMTP 25 port didn't. Also, the MX records are set correctly, but the DNS report says this:

Pass : MX records for domain
Failed : Mailserver connection test
HELO, MAIL FROM, RCPT TO, QUIT
Pass : Public IPs test MX records are public IPs conform RFC 1918
Failed : Mailserver greeting

I have to mentionate that my domain is hosting on my computer throw a free dns service.

After i scanned my ports, it says:
IP is responding on port 21 (ftp).
IP isn't responding on port 23 (telnet).
IP isn't responding on port 25 (smtp).
IP is responding on port 80 (http).
IP is responding on port 110 (pop3).

So.. how can i resolve this problem with the MX and SMTP ?

[Code Crafters]

A port conflict that stops Ability Mail Server running SMTP on port 25 means that another application is already using that port and only one application can bind to each IP / port pair.

To solve this you need to disable the application running on port 25. This will be another mail server. Disable or uninstall any other mail servers on that computer and usually most often Microsoft IIS is the application using up the port and this can be stopped via Control Panel -> Administrative Tools -> Internet Information Services (IIS) by opening the tree on the left to show the SMTP service, right click properties and select for the service not to start automatically with Windows.

If you are not sure what application is using port 25, open a command prompt (Run: cmd) and type "telnet localhost 25" from the mail server machine and this should give you a mail server welcome message showing the application name.