SFR Postmaster(y) page

To help the sender community, we are very happy to share our experience collected over the past years, about Mailbox providers. This article is about a historic provider in France: SFR Grand Public (,,,,, etc…). Postmastery integrates data from the aggregated Feedback Loop of SFR Grand Public, through its monitoring tool and its partnership with Signal Spam.

Please find the table of contents for this article below:

Market share and history of ISP

SFR is a French telecommunications operator. Founded in 1987, SFR was first specialized in mobile telephony. Over the years, the company expanded its services to include Internet access and television. In 2011, SFR became a subsidiary of the Vivendi group. In 2014, it was acquired by the Numericable group, thus becoming SFR Numericable. Finally, in 2016, Altice bought SFR Numericable and renamed it SFR. Today, SFR is one of the main telecommunications operators in France, offering a wide range of services to individuals and businesses.
From a deliverability point of view, SFR Grand Public uses a single infrastructure and therefore applies the same filtering policy to all of its electronic messaging services.

Anti-Spam Measures

To protect its messaging infrastructure, SFR Grand Public uses market solutions.

Feedback Loop

SFR Grand Public has partnered with Signal Spam and Validity to provide a Feedback Loop in ARF format, as well as an aggregated Feedback Loop, accessible only to Signal Spam members.

How does the SFR Grand Public aggregated Complaint Feedback Loop work and how can we access it?
SFR Grand Public's aggregated Complaint Feedback Loop is a file in CSV format that contains the volume of complaints by IP and by day. This aggregated Complaint Feedback Loop is available to Signal Spam members.

How does the SFR Grand Public Complaint Feedback Loop ARF work and how can I access it?
The ARF Complaint Feedback Loop consists of unit complaint reports in ARF format, sent to a dedicated email address. This ARF Complaint Feedback Loop is accessible to Signal Spam members, and also via the Validity Feedback Loop (1.500$ a year).

Postmastery's customers can track SFR complaint rates in the Reputation Monitor module of the Postmastery Console as well as tracking reputation and complaint data for IP addresses and domains from the world's leading anti-spam solutions including Spamhaus, Cloudmark, Abusix, SURBL, SORBs and Trend Micro.

SFR Postmaster technical and SMTP tweaks

The SFR Grand Public domains (,,,,,,,,,, mageos. com,,,,,,,,,,,, and all use the same MX record, Here are the three levels of constraints:

  • Concurrent SMTP connections per IP, based on reputation;
  • Messages per connection, based on reputation;
  • Connections per IP per hour, based on reputation;

SFR Grand Public recommends authenticating messages with both SPF and DKIM.

Common Error Messages

Here are some examples of error messages indicating a deliverability issue at SFR Grand Public.

421 4.7.0 Error: too many errors
450 4.7.1 Client X.X.X.X blocked: Service refused due to bad behavior SFR_IN_101
450 4.7.1 Client X.X.X.X blocked: Service refused due to bad behavior SFR_IN_102
450 4.7.1 Client X.X.X.X blocked: Service refused due to bad behavior SFR_IN_103
450 4.7.1 Client X.X.X.X blocked: Service refused due to bad behavior SFR_IN_104
450 4.7.1 Client X.X.X.X blocked: Service refused due to bad behavior SFR_IN_105
550 5.1.1 Recipient address rejected: User unknown
552 5.2.2 <>: Over quota
550 5.7.1 Email rejected per SPAM policy

At the end of each SMTP message indicating a block issue, there is an SFR Grand Public error code like SFR_IN_XXX. Each SFR Grand Public error code has a precise meaning.

Here is a (non-exhaustive) list of existing Error Codes :

Each SFR_IN code has a special meaning:

  • SFR_IN_ : SFR Grand Public code for an Inbound connection (incoming connection for the operator's servers)
  • The first number is internal information to SFR Grand Public
  • The last two digits:
    01: too many messages classified as Spam
    02: too many messages containing viruses
    03: too many SMTP errors (other than those linked to other SFR Grand Public codes)
    04: too many User Unknowns
    05: too many messages sent

Each message has its own trigger threshold based on a specific observation period. The appearance of one of these messages indicates a block for a total duration of 2 hours.

Do you have a specific error message you need help with? The Postmastery team is ready to assist, please share some details here.

Abuse Desk & Tech Support

In the event of a problem, SFR Grand Public has an abuse handling unit, which deals with issues related to the deliverability of emails on its infrastructure.
The contact address is
When contacting them, be sure to include the following information:

  • date of occurrence of the problem
  • sending IP(s)
  • sending host name(s)
  • sending domain
  • SMTP code returned by SFR Grand Public

More information
If you want more information about this topic, please send us a message via our contact form.
We are always happy to assist!

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