In Hosted Email Security(HES) / Email Security (EMS), outbound mails are rejected by UCEPROTECT, showing the following error,
550-Blacklisted in dnsbl-3.uceprotect.net: 550-Your ISP AMAZON-02 - Amazon.com Inc. US/AS16509 is UCEPROTECT-Level3 550-listed for hosting a total of XXXXX abusers.
MTA Logs show return message similar to,
host [x.x.x.x] said: 550-Blacklisted in dnsbl-3.uceprotect.net: 550-Your ISP AMAZON-02 - Amazon.comm Inc. US/AS16509 is UCEPROTECT-Level3 550-listed for hosting a total of xxxxx abusers. See: 550 http://www.uceprotect.net/rblcheck.php?ipr=x.x.x.x (in reply to RCPT TO command)
Based on the return message above, the email was rejected because UCEPROTECT blocked AWS ASN (A huge number of AWS IPs are blacklisted by UCEPROTECT). Trend Micro is actively working with AWS support to fix this issue, but this is out of our control.
Follow these steps:
- Check the status of the IP on the site, UCEPROTECT Network - Spam Database Query.
- Under Test, select ASN from the drop down list. Enter the ASN Value found from the MTA Logs. As an example, AS16509. Click Start Testing.
- Let the recipient server know that the issue is with UCEPROTECT and that they should whitelist our IPs. Trend Micro server IP addresses can be found on the following articles under the Inbound Servers section:
- Inform your affected recipient(s) to stop using UCEPROTECT if possible, because it blocks the entire AWS ASN (16509), which will accidentally injure the emails from HES/EMS and all other services hosted in AWS.
- At least, inform your affected recipients(s) to disable UCEPROTECT Level 3 check because Level 3 is overly aggressive and will cause collateral damages.