SQL Agent Job error

It may be really simple question, but at the moment I have a kind of mental loop and need your help to break it. SQL server 2016 is installed using a domain account. I didn't create an explicit login, there is only a standard generic NT SERVICE\MSSQL$XXX login and all SQL Agent Jobs like backup, rebuild indices and dbcc checkdb are running with no problems, but if I create an SQL job running a simple select on the user database like select * from [AdventureWorks2016].[HumanResources].[EmployeePayHistory] where 1= 2 I get an error Executed as user: [active directory account of the SQL Service]. Failed to initialize sqlcmd library with error number -2147467259. [SQLSTATE 42000] (Error 22050). The step failed. I have to create a login for SQL service domain account to fix an error. Any ideas what happens were? Is this a security feature of the SQL server? UPD: after a drill-down I've found an answer about sqlcmd error: it caused by msdb.dbo.sp_send_dbmail with @query parameter if the query in @query fails. But I do not have an answer to my main question: why I can't run a query over the user database using an SQL server service account. UPD2: UPD2: as I realized my description is not that understandable, sorry for that. One more try. An SQL server is installed to run using active directory accout A. That means, it I open services.msc I see that account as a login account of the service. This configuration was implemented via configuration file, not as an after-setup change. SQL Server logins doesn't contain account A, only generic NT SERVICE\MSSQL$XXX and NT SERVICE\SQLAgent$XXX which are a members of sysadmin role as usual. All SQL maintenance jobs (index maintenance, DBCC and backups) are configured using Ola's scripts and running without any problems also on user databases. If I try to create an SQL Server Job to query user database even if it's a simple query like select * from [AdventureWorks2016].[HumanResources].[EmployeePayHistory] where 1= 2 the query can't run. SQL server trace shows an error: "The server principal A is not able to access the database "AdventureWorks2016" under the current security context" If I create a login A and add it to the sysadm role the job runs, no problems, but it's absolutely clear, as a sysadm it should not have problems to query a database. The point I do not understand: all other SQL jobs are running using generic account in the background, so there is a kind of impersonification in SQL: accout A is using a generic login. As an additional information: if I create a Login for A I can't delete it because SQL server means, User is logged in, so SQl user uses it in the backupground to connect to the SQL and to impersonificate a generic login. Why it's not possible if I query a user database via SQL Agent Job? DrillDown 2nd: USE [msdb] GO BEGIN TRANSACTION DECLARE @ReturnCode INT SELECT @ReturnCode = 0 /****** Object: JobCategory [[Uncategorized (Local)]] Script Date: 19.01.2022 11:21:44 ******/ IF NOT EXISTS (SELECT name FROM msdb.dbo.syscategories WHERE name=N'[Uncategorized (Local)]' AND category_class=1) BEGIN EXEC @ReturnCode = msdb.dbo.sp_add_category @class=N'JOB', @type=N'LOCAL', @name=N'[Uncategorized (Local)]' IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback END DECLARE @jobId BINARY(16) EXEC @ReturnCode = msdb.dbo.sp_add_job @job_name=N'test_query_userdb_2Steps', @enabled=1, @notify_level_eventlog=0, @notify_level_email=0, @notify_level_netsend=0, @notify_level_page=0, @delete_level=0, @description=N'No description available.', @category_name=N'[Uncategorized (Local)]', @owner_login_name=N'sa', @job_id = @jobId OUTPUT IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback /****** Object: Step [query separate] Script Date: 19.01.2022 11:21:44 ******/ EXEC @ReturnCode = msdb.dbo.sp_add_jobstep @job_id=@jobId, @step_name=N'query separate', @step_id=1, @cmdexec_success_code=0, @on_success_action=3, @on_success_step_id=0, @on_fail_action=2, @on_fail_step_id=0, @retry_attempts=0, @retry_interval=0, @os_run_priority=0, @subsystem=N'TSQL', @command=N'select * from dbo.Users where 1=2', @database_name=N'StackOverflow', @flags=0 IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback /****** Object: Step [query] Script Date: 19.01.2022 11:21:44 ******/ EXEC @ReturnCode = msdb.dbo.sp_add_jobstep @job_id=@jobId, @step_name=N'query param', @step_id=2, @cmdexec_success_code=0, @on_success_action=1, @on_success_step_id=0, @on_fail_action=2, @on_fail_step_id=0, @retry_attempts=0, @retry_interval=0, @os_run_priority=0, @subsystem=N'TSQL', @command=N'EXEC msdb.dbo.sp_send_dbmail @profile_name=''my profile'', @recipients=''my email'', @subject=''ALERT: XX'', @query =''select * from dbo.users where 1 = 2''', @database_name=N'StackOverflow', @flags=0 IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback EXEC @ReturnCode = msdb.dbo.sp_update_job @job_id = @jobId, @start_step_id = 1 IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback EXEC @ReturnCode = msdb.dbo.sp_add_jobserver @job_id = @jobId, @server_name = N'(local)' IF (@@ERROR 0 OR @ReturnCode 0) GOTO QuitWithRollback COMMIT TRANSACTION GOTO EndSave QuitWithRollback: IF (@@TRANCOUNT > 0) ROLLBACK TRANSACTION EndSave: GO The same query runs as a 1st step of the job and crashes the job if it runs as a @query parameter of send_mail SP. There is no permission context change between steps.