Provide a list of confirmed VPS providers in README

[DLopezJr]

Since Vultr no longer allows opening port 25 [LINK], it seems wise to begin a list of VPS providers who allow it.

Providing a confirmed list of providiers in the README makes it easy for everyone to find. This will help new users like me be able to spin up a instance quicker with less issues.

[DLopezJr]

Hetzner

https://docs.hetzner.com/cloud/servers/faq/#why-can-i-not-send-any-mails-from-my-server

Why can I not send any mails from my server?

[...] That's why we block ports 25 and 465 by default on all cloud servers. [...} Once you have been with us for a month and paid your first invoice, you can create a limit request to unblock these ports for a valid use case. In your request, you can tell us details about your use case. We make decisions on a case-by-case basis.

As an alternative, you can also use port 587 to send emails via external mail delivery services. Port 587 is not blocked and can be used without sending a limit request.

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DigitalOcean

https://docs.digitalocean.com/support/why-is-smtp-blocked/

Why is SMTP blocked?

SMTP port 25 is blocked on all Droplets for new accounts to prevent spam and other abuses of our platform.

Even if SMTP were available, we strongly recommend against running your own mail server in favor of using a dedicated email deliverability platform.

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Vultr

https://docs.vultr.com/what-ports-are-blocked

What Ports Are Blocked?

Blocked by default

You may request these blocks be removed by opening a support ticket.

• TCP port 25 (SMTP)

[PhoenixBlade24]

I've basically stopped trying to set up my mail server, it's been a constant headache despite Luke's script. Besides, Vultr is basically no better than Azure or any other such alternative at this point. https://www.youtube.com/watch?v=LGwvLB7rhCE

[kubner]

found this nice guide if anyone is interested https://webshanks.com/vps-with-open-port-25/

[adamzea]

I'm pretty happy with Racknerd as that webshanks article lists as number 1. The region I got one with doesn't have IPv6 though.
Also using Oracle Cloud Pay-as-you-go account. Port 25 is blocked by default, but you can request that it be opened with a support ticket and it will be opened for any VPS created in your account including the limited "Always Free" resources.

[Tenari]

I was able to get everything working via ultahost.com annual plan and a service ticket to open port 25. script worked on debian 12