blacklist DNSBL servers - problem with Outlook

[jandiblik]

An user configured “Request a Delivery Receipt” and “Request a Read Receipt” in Outlook. But sometimes he got an answer about confirmation of reading marked as Blacklisted according DNSBL list. But if I check sender’s IP address - it is not in blacklist on these DNSBL servers. For example IP address: 136.143.191.44. We use Kaspersky Email Gateway + these DNSBL servers: cbl.abuseat.org and bl.spamcop.net

[Chrispcritters]

That IP address doesn't appear to be listed.

Can you provide the complete bounce message?