Outlook 365

Hi subscribed to Outlook 365 while I was buying a domain for my business. After that, I set up the email address. I am receiving the email to that email address but cannot send any. Every time i try sending an email out it comes back with an error

Delivery has failed to these recipients or groups:

Shaun  (email address removed for privacy reasons)
Your message wasn't delivered because the recipient's email provider rejected it.

Diagnostic information for administrators:

Generating server: YT2PR01MB8198.CANPRD01.PROD.OUTLOOK.COM

Remote Server returned '550 5.7.708 Service unavailable. Access denied, traffic not accepted from this IP. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653 AS(7910)'

Original message headers:

Received: from YT1PR01MB3913.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:d::32)
 by YT2PR01MB8198.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:b1::20) with
 Microsoft SMTP Server (version=TLS1_2,
 cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5709.21; Tue, 11 Oct
 2022 23:14:48 +0000
Received: from YT1PR01MB3913.CANPRD01.PROD.OUTLOOK.COM
 ([fe80::82e1:438e:7f0a:d493]) by YT1PR01MB3913.CANPRD01.PROD.OUTLOOK.COM
 ([fe80::82e1:438e:7f0a:d493%3]) with mapi id 15.20.5709.015; Tue, 11 Oct 2022
 23:14:48 +0000