IP Blocked

My emails are being rejected with the following message:

"domains@microsoft.com: SMTP error from remote server for RCPT TO command, host: microsoft-com.mail.protection.outlook.com (52.101.194.13) reason: 550 5.7.1 Service unavailable, Client host [xxxxxxxxxx] blocked using Spamhaus. To request removal from this list see https://www.spamhaus.org/query/ip/xxxxxxxxxxxxx...."

The above link shows the following message:

"xxxxxxxx has 1 listing

Spamhaus Blocklist (SBL) - Why is this resource address listed?

This IP or range has been observed to be involved in at least one of the following activities; sending spam, snowshoe spamming, hijacked IP space, or associated with spam services (web, dns, etc) or bulletproof hosting. For more information, read Spamhaus' listing criteria for SBL inclusion.

As a result, this IP is listed in the Spamhaus Blocklist (SBL)

Removal process

Due to this listing’s technical nature, Spamhaus will only accept delisting requests directly from your ISP. If you require removal from this list, please contact your ISP directly, and ask their abuse team to contact the Spamhaus SBL team."

Thanks in advance for your help!