The error message you have received is caused by the fact that Spamhaus is currently blocking your IP address.
To resume sending messages consistently from the affected IP address, you need to request an unblock using the Spamhaus procedure via the link provided in the error message:
- Go to https://check.spamhaus.org
- Enter the IP address shown in the error message (the IP address is at the end of the URL starting with "https://check.spamhaus.org/query/ip/")
- Click on "Show details"
- Tick the box at the bottom of the page and click "Next steps"
- Complete the information requested and click "Submit"
Spamhaus will process your request within 24-48 hours, so please be patient.
As a temporary measure to continue sending messages without waiting for Spamhaus to process your request, you have two options:
- Use one of our webmails (SOGo or Roundcube)
- Use a VPN or change your connection location