You spin up a VPS, install Gitea, and realize it needs to send email. You point it at port 25. Nothing happens. You try 587. Still nothing. Your provider is blocking outbound SMTP and they may not advertise it.
This comes up often enough that it's worth having a clear picture of what's happening and what the actual options are.
Why VPS Providers Block SMTP Outbound
DigitalOcean, AWS Lightsail, Linode, Vultr — they all block port 25 by default. Some block 587 too, or at least rate-limit it heavily. The reason is legitimate: open relays on port 25 are the backbone of spam, and a single compromised VPS can become a spam relay before you notice. Providers block it to protect their IP reputation and avoid getting listed.
The catch is that this affects self-hosted apps — Gitea, Ghost, Mastodon, Umami, anything that needs to send transactional email — without necessarily telling you upfront.
