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Port 25 (SMTP Outbound)

Closed by Default

Port 25 outbound is closed by default on all VMs and dedicated servers.

This protects shared IP reputation across the Euronodes network. A single misconfigured VM can get the entire /24 onto blocklists — cleanup takes weeks.

How to Get It Opened

Submit a ticket with a brief description of your use case.

We open without further questions

  • Running your own MX for inbound mail (outbound needed for bounces and relay between your own hosts)
  • Relay between your own servers in our network or elsewhere
  • Self-hosted transactional mail with proper SPF/DKIM/DMARC and low volume

We don't open for

  • Bulk outbound from app servers — use a dedicated provider (Postmark, AWS SES, Mailgun, etc.) over ports 587/465. They handle reputation, deliverability, bounces, and warm-up. We don't.
  • Direct-to-MX sending from PHP/Node/Python apps — same answer, use 587/465 to a relay.

Conditions When Opened

Rules that apply

  • Monitoring — outbound traffic is monitored. Sustained volume above normal patterns triggers an automatic alert. Spam complaints from Cogent, Spamhaus, Microsoft, or Google result in immediate port closure pending investigation.
  • PTR records — we set the initial PTR at provisioning. Subsequent changes are on request, max once per month per domain. PTR rotation is a known spammer pattern.
  • Per server, not per account — opening port 25 on one VM does not open it on others.
  • No transfer of permissions — if a VM is rebuilt, reinstalled, or migrated to a new IP, port 25 resets to closed.

What "Bulk" Means

Rule of thumb

If you'd be uncomfortable explaining the volume and content to a Cogent abuse handler — it's bulk, use a dedicated provider.

Order confirmations, password resets, and invoice receipts to your own customers = transactional. We're happy to support that.