Here is the error message, this started a week ago. Am able to receive emails but ones sent are not going through.
Delivery has failed to these recipients or groups:
@aol.com (@aol.com)
Your message couldn't be delivered. Despite repeated attempts to contact the recipient's email system it didn't respond.
Contact the recipient by some other means (by phone, for example) and ask them to tell their email admin that it appears that their email system isn't accepting connection requests from your email system. Give them the error details shown below. It's likely that the recipient's email admin is the only one who can fix this problem.
For more information and tips to fix this issue see this article: https://go.microsoft.com/fwlink/?LinkId=389361.
Diagnostic information for administrators:
Generating server: PH7PR16MB6144.namprd16.prod.outlook.com
Receiving server: PH7PR16MB6144.namprd16.prod.outlook.com
Total retry attempts: 4
******@aol.com
2/9/2024 1:14:41 PM - Server at PH7PR16MB6144.namprd16.prod.outlook.com returned '550 5.4.300 Message expired -> 421 4.4.2 Connection dropped due to SocketError'
2/9/2024 1:11:22 PM - Server at mx-aol.mail.gm0.yahoodns.net (98.136.96.92) returned '421 4.4.2 Connection dropped due to SocketError'