Yes, thanks, already read that information too. So. there is no other option but to ask the ISP to open a port.

Hi Port 587 ist for Mailclients already open and default (MSA) For MTA (Server to Server) ist Port 25 zu use. In my opinion Switch to a better VPS Service like keyweb.de or ask to open the Port . Arne Yes, it's all clear about the MTA. But in my case I can't change the VPS. We just moved our server...

Hello! Please help me to set up Postfix. I need it to send mail through port 587. Port 25 is closed by the VPS provider. Keyhelp is installed on a clean Ubuntu 20.04. By default Postfix sends mail on port 25. Of course, I always get a "connection timeout" error. There are a lot of manuals ...