How to send emails via smtp with proxy?

Question

symfony

What we have:
1) VPS with ubuntu 16.04
2) Framework Symfony 4 version
3) Admin panel with the function of sending emails via smtp
What you need: make it possible to send emails through a proxy.
Additional information: there is no information about this in the documentation for the mailer's lib.
Interested implementation options: any options, even the most perverted ones.
Screenshots

Adding SMTP

Sending letter

Answer 1

Problem solved. Installed redsocks. I added a proxy in the panel, when added, my script generates a new redsocks config

Answer 2

Sending letters through a proxy is essentially an impossible task. Only if we are not talking about specialized software that can map ports and forward them through a proxy.

Answer 3

There is no concept of "proxy" in SMTP. There is a concept of "relays", but if you are not allowed there, then they are not allowed. Open relay is now a rarity and is considered a mistake and is accordingly banned mercilessly.
And besides, it is still impossible to hide the fact of sending from the vasyan.cool computer - unless you have access to the relay and the ability to install filters there.