Here for example the email couldn't be delivered to the recipient which are using O365 (host xxxxxx.mail.protection.outlook.com) as mail provider. There our IP 188.8.131.52 was blocked by Spamhaus.
Not delivered - 04/29/2021 09:44:37 (via TLS 1.2) -host xxxxxx.mail.protection.outlook.com[184.108.40.206] said: 550 5.7.1 Service unavailable, Client host [220.127.116.11] blocked using Spamhaus. To request removal from this list see https://www.spamhaus.org/query/ip/18.104.22.168 AS(1440) [VE1EUR03FT034.eop-EUR03.prod.protection.outlook.com] (in reply to RCPT TO command)
Here on this page you can check the current status:
If the IP is not listed there anymore then please open a case with Trend Micro Support.