German mailbox providers overview

Germany is an important region for ecommerce and email marketing. United Internet (gmx,, 1&1 and has the largest share of the market, owning 44% of active mailboxes. Deutsche Telekom, the market leader in terms of broadband customers, holds second place in terms of active mailboxes. 

The 2013 Publicare E-mail study reported that the rest of the market is divided between:

  • Hotmail (9%)
  • Gmail (8%)
  • Yahoo (7%)
  • Freenet (4.6%)
  • AOL (3%)  
What remains is covered by providers like Vodafone, EWE and UnitedMedia, who together comprise 4% of the market.

There is little movement of subscribers between mailbox providers in Germany. Once
subscribers choose an email provider, they tend to stay with them and keep the same email account for years.

Germany is Android's largest European market for mobile and accounts for Gmail's increased market share.

Legal authority
German mailbox providers expect senders to know and adhere to the laws governing email communications in Germany. Germany has some of Europe's strictest privacy and anti-spam laws. The Düsseldorfer Kreis (the assembly of the German data protection authorities) provides information that anyone interacting with German customers via email should be aware about. This information is not available in English on the Government's website.

Although there is some legal debate within Germany as to what constitutes confirmed consent, German law requires that consent be obtained from the subscriber prior to sending any marketing email. This consent should be transparent, unequivocal and conscious. The statement of consent should:
  • Inform subscribers who they are doing business with
  • Name third-party partners that may have access to subscriber data
  • Include information about subscribers' right to revocation
  • Provide an unsubscribe address
After the initial consent, German law requires marketers to secure confirmed opt-in. This means following up with a confirmation email and recording and saving the confirmation details. Simply recording the IP address is insufficient; senders must save the email detailing the confirmation. In addition, marketing messages sent to friends referred by customers are considered illegal spam. Some mailbox providers, specifically United Internet, consider confirmed opt-in mandatory.

Request for Comment compliance
The largest German mailbox providers are compliant with the Request for Comment (RFC) documents that
are applicable to email. (RFCs describe suggested practices relevant to the Internet but not all are applicable to email.)

German postmasters expect email marketers to be RFC-compliant. Although listing all of the RFCs relevant to email is beyond the scope of this article, the most basic on
es relevant to German MBPs include:
  • RFC5321: Simple Mail Transfer Protocol
  • RFC5322: Internet Message Format
  • RFC2369: The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields
  • RFC2368: The mailto URL scheme
Members of Return Path's Certified Sender Program receive benefits when sending to the millions of Hotmail and Yahoo! accounts in Germany. A large portion of the market is covered by the Certified Senders Alliance (CSA), a program created by the German Direct Marketing Association in cooperation with eco. CSA members benefit from the program's German-centric coverage.

The CSA whitelist covers half of the German market in terms of total mailboxes reached. The compliance and support methods used by CSA are very different from Return Path's Certification Program. For example:  
  • CSA publicly names senders who have received more than three reprimands for sending unlawful spam on its website.
  • The program requires manual intervention (through live phone complaints).
  • Complaints are processed through eco's hotline.
  • More severe violations are handled by a complaints committee.
Unfortunately, CSA does not provide any data to its certified senders that could be used as an early warning system and help marketers improve their email programs.

Filter technology
Most German mailboxes are protected against spam by CYREN (formerly Commtouch). Commtouch acquired eleven, a German-based spam filter technology company, in 2012 
and then in 2014 announced it was operating under the name of  CYREN. The mailbox providers using eleven may not have transitioned to CYREN technology; they may still be using the same eleven spam filter they were previously using.

The largest mailbox providers in Germany have home-grown anti-spam filter systems and never rely on just one filter or methodology. IP addresses are checked against several reputation scoring systems, and mail content is analyzed and subjected to the
mailbox providers' content analysis policies.

The most commonly used external blacklists in Germany are the Spamhaus blacklists and the Spam Uniform Resource Identifier Real-time Block List (SURBL), but mailbox providers have their own, internal blacklists as well.

Feedback loops
As a sender, it is important to keep on top of who does not want your mail, since some subscribers do not take the time to unsubscribe. Monitoring complaints via a feedback loop (FBL), when available, can be very helpful.

Neither T-Online (Deutsche Telekom) nor United Internet currently provide this kind of FBL service to senders. The T-Online postmaster states: "In accordance with the RFC standard, it may be assumed that the sender of a rejected message will automatically receive a corresponding bounce e-mail. There is therefore no feedback loop for" 

This approach ignores the fact that most FBLs are based on complaints (when the subscriber hits the This is Spam button), not hard bounces. Hopefully, German mailbox providers will eventually provide automated, IP- or domain-based FBLs for senders. In the meantime, senders should make unsubscribing easy and use engagement metrics such as opens and clicks to ensure they are sending content relevant to the subscriber.

While German law is very concise when defining spam, mailbox providers take a different perspective when deciding whether mail should be delivered or not. For them, spam is any mail that a subscriber does not want to receive.

At GMX, if subscribers can demonstrate that they continued to receive mail from a sender after requesting that the mail stop, the abuse desk team may block the sender's IP address permanently. This is a manual process and the decision is made by the abuse desk team; it is not automatic or based solely on This is Spam complaints.

Email marketers should:
  • Use engagement metrics like opens and clicks when deciding on sending frequency and content 
  • Process bounces diligently and automatically remove addresses that have hard bounced because they are no longer valid
According to German postmasters, how senders handle the unsubscribe process indicates how serious they are about following industry best practices. The process should 
be as simple as possible and:
  • Enable subscribers to unsubscribe with one click
  • Require no passwords, completion of forms or authorization
  • Suppress the email address immediately
Reminder mails
Based on conversations with postmasters in Germany and throughout Europe, Return Path recommends marketers send no more than three mails total and no more than one per month.

Connection and throughput
United Internet postmasters strongly suggest that senders open no more than five simultaneous connections when sending. They are flexible on throughput so use your discretion and be reasonable. If you send too many messages too quickly, expect to receive a 421 throttling message.

Other German postmasters prefer senders to open no more than two simultaneous connections. The
connection and throughput settings in Europe are generally much lower than in North America and lower than what Return Path recommends for global providers (Microsoft, AOL, Gmail and Yahoo!). This is due to infrastructure and resources.

Postmaster pages
German postmaster pages are some of the most informative in Europe. The sites include information on technical requirements, best practices, bounce code meanings and more. You can also contact the abuse desk team from these sites
directly. The most relevant sites are:
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