Failure sending mail: One or more errors occurred

Hi. I am using Visual Studio 2017. I have a lot of subscribe's reports, since last Monday (08/01/2024), they just stopped. a message: Failure sending mail: One or more errors occurred appears.

When I checked the RS log, a error message is displayed:

emailextension!WindowsService_0!5378!01/10/2024-09:34:21:: e ERROR: Error sending email. Exception: System.AggregateException: One or more errors occurred. ---> System.Net.Mail.SmtpException: Failure sending mail. ---> System.IO.IOException: Authentication failed because the remote party has closed the transport stream.

I have no ideia what it means. The person who installed/configured SSRS didn't work in here anymore...

Can someone helps me?