Best practices

mail.com is committed to providing a trustworthy and secure service to its users. For this reason, careful evaluation of incoming emails and protection against unsolicited emails are top priority.

The following rules apply for senders of mass mails:

To avoid flooding the inbox with mass mails that are not solicited and not wanted, emails that do not comply with established standards such as those of the M3AAWG Working Group and the Certified Sender Alliance (CSA) must, in the interest of our users, first be expressly designated as wanted by the users before they are delivered to the inbox.

Recommendations for bulk mailers:

  • The Messaging Anti-Abuse Working Group (M3AAWG) cooperates with large and important internet service providers to regularly draft a guide to sending emails. Use this guide as the basis for your work.

  • Send emails only to recipients from whom you have received consent to receive bulk emails such as newsletters. We recommend e.g. using the double-opt-in-process.

  • Imprint mandatory: The contractor or the sender's contract partner must be clearly identifiable for the recipient.

  • The recipient must be able to quickly and easily unsubscribe from a mass email (newsletter, advertising, etc.).
    As such, every email must include the corresponding link. However, your newsletter should ideally meet the criteria of the new internet standard, RFC 8058. If we recognize your email as a legitimate newsletter and your email also fulfills this standard, the standardized newsletter unsubscribe link will be shown on GMX. This offers the user a convenient way to unsubscribe. If your newsletter does not meet the new RFC standard, then providing a valid reply address can also be an option for unsubscribing.

  • To preserve your domain's good reputation, send emails only to our customers who actually wish to receive and read emails. This reduces the probability of spam complaints which could probably result in sanctions against your domain.

  • Remove email addresses from your lists that have been repeatedly and therefore permanently unreachable. If you attempt to deliver mail to multiple unknown (or disabled) mail.com accounts, you will be temporarily blocked. We reserve the right to block you permanently in this case.

  • As a sender of mass mails we recommend that you participate in the Certified Senders Alliance. More information is available here.

Problems with delivery despite following our recommendations:

  • If your attempts to send email to us are rejected despite following all recommendations, our mail system will produce an error message. It provides information about the cause of the rejection and whether mail.com's postmaster must be contacted to remedy the cause. An example of a cause could be that your IP address or domain is listed on an internal blocklist.

  • It may happen in the case of bulk mailings that throttling is performed by our system despite the IP warmup. If this occurs, you can also contact us via the relevant error message.

  • Here is an example of an error message:
    421-mail.com (mxgmxus101) Nemesis ESMTP Service not available
    421-Service unavailable
    421-Reject due to policy restrictions
    421-For explanation visit https://postmaster.mail.com/error-messages?ip=&c=poli

Glossary

  1. The Messaging, Malware and Mobile Anti-Abuse Working Group is an international association consisting of internet service providers, anti-spam and anti-virus technology producers as well as other interested parties. The association offers a member forum for the exchange around the topic security in telecommunications: https://www.m3aawg.org/
  2. RFC Indicates documents that describe the technical or organizational guidelines for the internet.
  3. Opt-in describes a procedure in which a consumer explicitly consents to be contacted for advertising purposes. In addition, the Double-Opt-In procedure makes sure that the email address provided really belongs to the consumer. In order to do that, usually a verification link will be sent to the email address. This verification link has to be accessed once before getting added to a distribution list. That way, it is possible to prevent unauthorized third parties from adding email addresses to distribution lists.