I'm confused. Why would your ISP block INBOUND port 25? Most ISPs block OUTBOUND port 25 for customers with dynamic IP address - they don't want their customers sending spam. But if you are paying for a static IP address - and I assume you are if you are trying to run an email server - then you should be entitled to receive inbound on any port (perhaps subject to limitations on volume). Otherwise what's the point of paying them extra for your static IP?

As for outbound port 25, I would also question the value of a static IP address if they block it.

Hi 

I'm using Mercury v4.7 that was installed with XAMPP package. Unfortunatelly my ISP blocks port 25 so I set SMTP to listen on 587 I also enabled ssl/tls. My domain is set properly and mx is resolved properly.

The problem is that I can't receive emails sent from gmail or other external mail services.  I assume this is because gmail is trying to communicate via port 25. I checked and it is possible to telnet my server on port 587. Is there a way to tell other servers to connect via 587. 

Thanks in advance 

Unfortunately not, SMTP servers communicate with each other on port 25 only. To solve this you would need to involve some third part for relaying, as described in this thread:

http://community.pmail.com/forums/thread/7734.aspx 

/Rolf