IONOS is committed to providing its users with a trustworthy and secure service. Accordingly, carefully evaluating incoming emails and taking action against unwanted messages (spam) is a top priority.

Information for Email Administrators

The following notes apply to the operators of the email services:

Respect the recipients' wishes not to receive unsolicited emails

As soon as a IONOS user can prove that the sending of unsolicited emails has not been stopped despite a corresponding notification, we reserve the right to permanently block the corresponding services.


Observe legal requirements
Observe the legal requirements applicable in your country. For the US, for example, these are described in the Can-Spam Act. Please note that you can be held responsible as the sender of mass mails if you have not obtained the recipient's consent.

The Messaging Anti-Abuse Working Group (MAAWG) works with large and important service providers on the Internet to regularly develop guidelines for sending emails, which you should consider.


RFC conformity
Emails and communication with our servers must comply with the standards defined in the current RFC.


No reception from dialup areas
The email may not be sent directly to our mail servers from dialup networks. Emails from users with a dynamic IP address must be sent via a smart host or SMTP relay server protected against misuse.


Reverse DNS entry
A Reverse DNS entry (FQDN) of the delivering server must exist.


Correct HELO
A meaningful and plausible HELO/EHLO in the sense of RFC 5321 must be sent.


Sender Policy Framework
We check the SPF records at the customer's request. The sender addresses of forwarded emails should therefore be rewritten using SRS.


Securing the sending servers against misuse
The sending server must be protected against unauthorized access.


RBL lists
We check various established RBL lists. Make sure that your server is not on such a list. You can check this at

Guidelines for Mass Mailers

The following principles apply to senders of mass mails:


Address list cleanup

The sender must immediately remove email addresses from his mailing lists if hard bounces occur after sending to these addresses. If delivery attempts are made to numerous unknown (or meanwhile deactivated) IONOS mailboxes, the system is temporarily blocked. In such cases, we also reserve the right of permanent suspensions.


Imprint obligation
The customer or the contractual partner of the sender must be clearly recognizable to the recipient. It is recommended that requested bulk emails contain valid, non-electronic contact information of the sender including the telephone number and a real address.


Double Opt-in
Send emails only to recipients from whom you have the consent to receive mass emails such as newsletters. The use of the double opt-in method is recommended, for example.


The receipt of mass mail (newsletter, advertising, etc.) must be quickly and easily revocable for the recipient. A corresponding reference should be contained in a respective email.