In France ISPs mailboxes still represents a large chunk of the targeted B-to-C segment.
Today, we are taking about one the largest french ISP named as SFR.
The largest french ISPs are known to be using the filtering systems from Vade Secure.
In this post we’ll look at the GU_EIB bounce codes and their meaning.
GU_EIB_02 : « 5.7.1 <email.deliverability.guru.com[xxx.xxx.xxx.xxx]>:
Client host rejected: Abus detecte GU_EIB_02 »</email.deliverability.guru[xxx.xxx.xxx.xxx]>
The above listed SMTP code GU_EIB_02 is characteristic of a list hygiene issue and will be returned if the threshold of invalid addresses is too high therefore generating a temporary block.
GU_EIB_04 : « 5.7.1 <email.deliverability.guru.com[xxx.xxx.xxx.xxx]>:
Client host rejected: Abus detecte GU_EIB_04 »</email.deliverability.guru[xxx.xxx.xxx.xxx]>
The second SMTP code GU_EIB_04 indicated that your messages have been considered as being “spam” which will result in a temporary block.
Both of the above blocks are generated following unusual invalid addresses or spam thresholds.
What is being considered?
For your messages to generate the above listed blocks, you would have experienced the following within a window of about 5 minutes:
- Exceeding the threshold of 25% of messages received at the ISP being marked as spam
- Exceeding the threshold of 25% of messages received at the ISP being directed to invalid users
If you are experiencing such issues, the blocking usually last for 20 minutes.
If new occurrences of spam or invalid users are generated then the block will be renewed until the problem stops.
Please find below the list of domain names bound to SFR: