What Does “554 5.7.1 Service unavailable” Mean?¶
If you see an error like “554 5.7.1 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked you may be infected” this error message is displayed because the internet gateway (identified by the public IP address XXX.XXX.XXX.XXX) that you were using when sending your email is blacklisted by Spamhaus Project due to a high probability of spam. You can go to the Spamhaus IP lookup and enter your IP address into the lookup tool to reasons why the address may be blocked. .
Spamhaus Project is a tool used by Gandi to assess the trustworthiness of emails that travel through our platform. Put simply, Spamhaus Project allows us to know if the IP address used when sending your email is considered as being reliable or not. In your case, your sending is not deemed reliable, and the transmission of email is therefore blocked in order to avoid any risk of the sending of spam to others.
In accordance with Gandi’s values and commitments, including binding contractual provisions, made with regard to the GandiMail service, the use of this service relies at no point on the study of your private communications’ content and only aims at enhancing our users and platform’s security by mitigating service abuse and spam risks.
If your public IP address is blacklisted, you or your IT team will need to follow the process as outlined on the Spamhaus Project website.
To do this, click on the “CBL” link present in the report you found by looking for your IP address in the Spamhaus IP lookup. After the captcha verification, you will see a detailed report for this public IP address, and the reasons for it being blocked. This information will be useful for identifying the source of the potential network internal breaches and to correct them.
Once these problems have been corrected, you will have the opportunity to request the delisting of the public IP address via the “Remove” button on the bottom of the above page.
Please note that if the security issues are not addressed and you still use the same setup and configuration (including the IP address), you will find yourself in the same situation a few days later.
While you are working on addressing the issues with Spamhaus, you can one of these temporary solutions.
You can also configure your email application (Outlook, Mail, Thunderbird, etc) so that it uses the SMTP (outgoing mail server) of your internet provider to send emails. You may be able to find the SMTP for your email provider in this list.