Roundcube only Sendung Emails to some Domains

I have A Ubuntu Server on which im Using Roundmail for my Email Service.

Basically i Can receive Emails and send emails to f.e. @gmail.com but not for other domains.

instead im Just getting

host mail-01.dd24.net[193.46.215.141] said: 550 5.7.1
Service unavailable; client [77.68.4.36] blocked using cbl.abuseat.org (in
reply to RCPT TO command)

Final-Recipient: rfc822; domain@domain.info
Original-Recipient: rfc822;domain@domain.info
Action: failed
Status: 5.7.1
Remote-MTA: dns; mail-01.dd24.net
Diagnostic-Code: smtp; 550 5.7.1 Service unavailable; client [77.68.4.36]
    blocked using cbl.abuseat.org

but when im sending f.e. from my gmail to my domain@domain i can receive it

anybody having an Idea?