In the last few days, we are experiencing issues with generating and sending out reports via the SMTP server. Some of the reports are successfully generated and sent but there is an increasing number of those that fail. Looking at the logs the error is:
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.
Googling the error it appears the issue is caused by an invalid TLS security protocol. According to multiple sources, the solution should be to update the TLS protocol to 1.2. How would one go about updating the security protocol on SSRS?
one of the sources: How to fix the error "Authentication failed because the remote party has closed the transport stream"
EDIT 28/10/2021:
For anyone experiencing the same issue. Our support partner investigated this and it appears to be due to service degradation with Microsoft Exchange Online. Microsoft logged the following incident:
Title: Some users are intermittently unable to access their mailboxes through multiple connection methods when using TLS 1.0
User Impact: Users may intermittently be unable to connect to Exchange Online through IMAP, SMTP, and POP3 while using TLS 1.0.
More info: Users of the legacy Transport Layer Security (TLS) version 1.0 are experiencing intermittent failures when attempting to connect to Exchange Online from IMAP, SMTP, and POP3.
Current status: Our monitoring indicates that the fix has been successful in mitigating impact in the section of infrastructure. We're now rolling out this fix to the rest of the impacted environment.
Scope of impact: A small subset of users of TLS 1.0 are intermittently unable to connect to Exchange Online from IMAP, SMTP, and POP3.
Root cause: A CAFE TLS configuration issue is preventing some users from connecting to the Exchange Online service through IMAP, SMTP, POP3.
EDIT 02/11/2021: Apparently, Microsoft has rolled out a fix for this issue on 29/10/2021.