Unblocking port 25 for sending emails

Valid for Cloud Servers, Dedicated Servers, and Server Power Deals managed in the Cloud Panel.

For security reasons, port 25 (SMTP) is blocked by default. If you want to send emails via your server, we can unblock this port for you.

Please ensure that your server meets the following technical requirements. Our team can only proceed with unblocking the port if these settings are configured correctly.

• Valid host name: Your server requires a valid, fixed domain name (fully qualified domain name, or FQDN for short). Example: example.com
• Reverse DNS (PTR): The internet needs to know that your IP address really belongs to your server name. To do this, you need a reverse DNS entry to point your IP back to your hostname. The following article explains how to configure a reverse DNS entry in the Cloud Panel: Overview: Public IP
• SPF entry: An SPF entry must be present in the DNS settings of your domain. Sender Policy Framework (SPF) is a security protocol for email communication. It requires the domain of the email address to identify in a DNS entry which servers are authorised to send emails on its behalf. The receiving mail servers trust the authorised servers and accept emails from these servers as trustworthy.

If the three requirements above are met, please contact IONOS customer service by phone.