@zedomingues 587 is only for clients, not servers. port 25 supports the same encryption algorithms that 587 uses so it's just as secure (when it's told to do so).
Port 25 is mainly used for server-to-server communication and it will always need to be that way according to the RFC for SMTP.
considering that the whole world considers port 25 to be a less secure and more spam-friendly port, is there any way to configure my installation to send emails through port 587?
The "consideration" of port 25 by the whole world is because it's been the port of choice since the invention of the simple mail transport protocol, SMTP, meaning this is how it works since the beginnings of this technology, before it even was known as "The Internet", and at that MOST EMAIL CLIENTS are set by default to use port 25 for email sending protocol (SMTP), thus not a server-to-server- only communication protocol.
The use of port 587 for SMTP sever would be to use with SSL and/or TLS encryption and would be much easier to set as is, if you will, if you use an email marketing software from your server (which would allow you to use port 587 as a secured sending port) and / or if you set your SMTP using a third party as AWS SES or SendGrid or Mailchimp or any in the like.