SQL SERVER – Database Mail Error: The SMTP Server Requires a Secure Connection or the Client Was Not Authenticated. The Server Response Was: 5.5.1

Pinal Dave’s  blog has been one of my go-to blogs as a SQL DBA for a long time.

I remembered a similar situation in one of our servers when he blogged about a DB mail issue with the error message.

In our scenario, a SQL Server task using the SSIS Package to send emails to the development team was failing with the error below.

The SMTP Server Requires a Secure Connection or the Client Was Not Authenticated. The Server Response Was: 5.5.1

Only one of the server’s jobs that used Database mail was experiencing this difficulty. While successful tasks had part of the connection string as ‘EnableSSL= True,’ further investigation of the package revealed that unsuccessful jobs had part of the connection string as ‘EnableSSL= False.’

The connection string for the job that was failing was set to ‘EnableSSL = False’.

The job was corrected when the connection string was fixed, and it was running successfully.

For more fixes related to this error message see Pinal’s blog posts

https://blog.sqlauthority.com/2018/06/30/sql-server-database-mail-error-the-smtp-server-requires-a-secure-connection-or-the-client-was-not-authenticated-the-server-response-sas-5-5-1/

https://blog.sqlauthority.com/2018/07/04/sql-server-database-mail-error-the-smtp-server-requires-a-secure-connection-or-the-client-was-not-authenticated-the-server-response-was-5-5-1-using-gmail/

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