[CentOS] can't send email from my new centos 8

Mon Jan 20 21:24:05 UTC 2020
Jonathan Billings <billings at negate.org>

On Mon, Jan 20, 2020 at 06:04:47PM -0300, V. M. Tame-Reyes wrote:
> I apologize in advance, for the following could be too simple, but I can't
> figure it out.
> I configured a vps using centos 8, all is working fine but I'm not able to
> send email from this server.
> I tried
> $ telnet smtp.mailtrap.io 25 but it doesn't work
> yet
> $ telnet www.google.ca 80 does work
> and particularly
> $ telnet smtp.mailtrap.io 2525 does work too.
> I temporarily disabled the firewall, and selinux, but no luck.
> Can anyone provide any pointers?

Are you configuring your VPS running CentOS 8 to run an SMTP server on
port 25, or are you trying to make your VPS running CentOS 8 talk to
an external SMTP server?

It sounds like you are trying to make your VPS talk to an external
SMTP server.  By default, the firewall shouldn't prevent outbound
connections.  However, some VPS providers, as well as residential
ISPs, do block outbound traffic to port 25, in an attempt to prevent
compromised systems from sending spam.  I suggest you look at the
documentation for your VPS provider and see if you are permitted to
send SMTP mail from the host.  You may need to relay mail through an
authenticated SMTP relay run by the VPS provider.

Jonathan Billings <billings at negate.org>