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 below:
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 (e.g. 16509).
- Click Start Testing.
Let the recipient mail server administrator know that they can whitelist Trend Micro server IP addresses, which can be found on the following articles under the Inbound Servers section:
For HES, the following additional IP addresses may be used:
- Inform your affected recipient(s) to disable UCEPROTECT Level 2 and Level 3 check, because these create collateral damages without additional protection from real spammer IPs. In particular, Level 3 is overly aggressive and the collateral damages will block huge amount of legit emails.
- If the affected recipient domain is using WGET to get UCEPROTECT black list, they can just download the Level 1 file without downloading the Level 2 or Level 3 files.
- If the affected recipient domain is using RSYNC to synchronize UCEPROTECT black list, they can sync to the dnsbl-1 (Level 1) RBLDNSD file, without syncing to dnsbl-2 or dnsbl-3. Below is an example:
rsync -azv rsync-mirrors.uceprotect.net::RBLDNSD-ALL/dnsbl-1.uceprotect.net /targetdir
- If they are using DNS zone, they can update the zone to dnsbl-1.uceprotect.net for only Level 1 check.
For example, modify Postfix main.cf with:
smtpd_recipient_restrictions = … reject_rbl_client dnsbl-1.uceprotect.net,