SMTP / Port 25 Policy at Infrawire

Overview

To protect the integrity of our network and the reputation of our IP ranges, Infrawire blocks outbound SMTP traffic on port 25 by default on all servers. This document explains why this restriction exists, what alternatives are available, and how customers can request an exception through our Paris (France) location.

Why Port 25 Is Blocked by Default

Port 25 is the standard port used for direct, unauthenticated mail relay between mail servers. Because it requires no prior authentication, it is the port most commonly abused by:

• Spammers who compromise or rent servers to send bulk unsolicited email
• Botnets that use hijacked servers to distribute phishing or malware campaigns
• Open relays, misconfigured servers that let any third party send mail through them without authorization

When abuse occurs, the sending IP address (and often the entire surrounding IP range) gets added to public DNS-based blocklists (DNSBLs) such as Spamhaus or SORBS. Once an IP range is blocklisted, all customers hosted on that range — not just the abuser — suffer degraded email deliverability, since major mail providers (Gmail, Outlook, Yahoo, etc.) will reject or spam-flag mail originating from listed ranges.

Blocking outbound port 25 by default is a preventive measure that:

• Stops automated spam scripts and compromised servers from sending unauthenticated bulk mail
• Protects the reputation of Infrawire's shared IP space
• Reduces the likelihood of the entire network being blocklisted
• Encourages the use of authenticated, monitored mail-sending methods (see below)

Recommended Alternatives

For most use cases, we recommend using an authenticated submission port instead of raw port 25:

We also recommend using a transactional email provider (e.g., a third-party SMTP relay service) for application-generated mail such as password resets, notifications, or invoices. These services handle authentication, reputation management, and deliverability on your behalf, and are generally the fastest way to get reliable mail delivery without needing port 25 access at all.

Requesting Port 25 Access — Paris (FR) Location Only

For customers who specifically require direct outbound SMTP on port 25 (for example, running your own mail server), Infrawire allows this exclusively on servers hosted in our Paris, France location. This restriction lets us apply enhanced monitoring and abuse-prevention controls that we are not able to guarantee across all regions.

Key Conditions

• Location: Available only for servers physically hosted in Infrawire's Paris (FR) datacenter.
• Cost: A monthly fee of €15 per server applies for enabling port 25 outbound access. This fee covers the additional monitoring, IP reputation management, and abuse-handling overhead associated with SMTP traffic.
• Eligibility: Requests are reviewed on a per-server basis. Infrawire reserves the right to decline or revoke access in cases of suspected abuse.
• Monitoring: Servers with port 25 enabled are subject to ongoing outbound traffic monitoring to detect abnormal sending patterns (e.g., sudden spikes in volume, high bounce rates, spam complaints).

How to Request Access

1. Ensure the target server is provisioned in the Paris, France location. If it is not, a migration or new server order will be required.
2. Submit a support ticket requesting "Port 25 SMTP unblock", including:

• Server ID / hostname
• Intended use case (e.g., mail server, newsletter platform, transactional mail)
• Expected sending volume

3. Once approved, the €15/month fee will be added to the billing for that server.
4. Port 25 will be unblocked on the server's outbound firewall rules.

Abuse Policy Reminder

Regardless of location or port configuration, all mail sent from Infrawire infrastructure must comply with our Acceptable Use Policy, including:

• No sending of unsolicited bulk email (spam)
• Proper SPF, DKIM, and DMARC configuration for any domains sending mail
• Maintaining a valid abuse contact and unsubscribe mechanism for any bulk mail
• Prompt remediation of any compromised server used to relay spam

Violation of these terms may result in immediate suspension of port 25 access, additional review, or account-level action.

Summary

Updated on: 30/07/2026