When I try to use fetchmail to receive mail from the ISP, I'm getting the following error message:

user@correo: fetchmail
fetchmail: Failed verification of server certificate: self signed certificate
1 message to "userISP" in "hostISP" (2083 bytes)
reading message "UserISP@hostISP": 1 1 (2093 bytes). fetchamail: connecting to localhost:smtp [1: 1/25] failed: fefused connection.
The error is in Spanish. I've translated.

But if I connect by telnet localhost 25 connect well. And if I try on another pc on the same network also connects well

If it helps, internal mail does not work

I hope your help.
Thank you