Tech-Xpress.com is a site on the ISPconfig box I have running, I have setup several emails on it. Port 25 has NEVER EVER been blocked by provider or firewall. It's obviously showing on the server which means it has gotten all the way there.
I have outlook express configured with sever accounts all on different non local servers. I used one of those accounts to send an email to email@example.com
. It then went out from my computer through my router to my ISP into their servers then got the MX records went through my router into the ISPconfig server and the connection was refused at that point. What I find strange is that I can do a telnet to the server on the same port and it works fine. not a telnet localhost 25 but rather a telnet 192.168.1.4 25. I haven't been away from home lately but if I get outside my network in the next day or two I'll try a telnet from telnet 188.8.131.52 25 and see what happens.
*note: I used to work at my current ISP so I know their setup.