Ports opened for SMTP (587 / 465), still cannot connect

[ClassyMiles859]

Hello,

My server hosts a website that requires an SMTP connection to an external mail server (Either 587 or 465).

I configured the following ports in firewalls:

[root@60b250e9c256a30001258cd5 public]

# firewall-cmd --zone=public --permanent --list-ports
10090-10100/tcp 587/tcp 465/tcp

However, I am still unable to connect to the external mail server.

Both ports are closed, according to https://portchecker.co/.

When I try to connect to them via telnet from my own PC, the connection is lost.

According to my email provider, the problem is on my end....

Do you have any ideas what this could be?