User Executes Stored Procedure That Executes sp_send_dbmail; receives email but also gets error Cannot alter the queue 'ExternalMailQueue', because it does not exist or you do not have permission.

Question

Using SQL Server 2012 SP1
I have a user that is submitting a procedure that uses sp_send_dbmail.  I have also noticed that they have the following code in their procedure
DECLARE @rc INT
IF NOT EXISTS (SELECT * FROM msdb.sys.service_queues
WHERE name = N'ExternalMailQueue' AND is_receive_enabled = 1)
EXEC @rc = msdb.dbo.sysmail_start_sp
The user submits the procedure and she gets the email but she also gets the following error message:
Msg 15151, Level 16, State 1, Procedure sysmail_start_sp, Line 8
Cannot alter the queue 'ExternalMailQueue', because it does not exist or you do not have permission.
Mail (Id: 2402) queued.
(1 row(s) affected)
I have granted execute to sp_send_dbmail and sysmail_start_sp.  I have also granted select to service_queues.
Does anyone have any solutions for the above error message?
lcerni

Answer 1

The contents of sysmail_start_sp is this:
CREATE PROCEDURE sysmail_start_sp
AS
    SET NOCOUNT ON
    DECLARE @rc INT
   DECLARE @localmessage nvarchar(255)
    ALTER QUEUE ExternalMailQueue WITH STATUS = ON
    SELECT @rc = @@ERROR
    IF(@rc = 0)
    BEGIN
      ALTER QUEUE ExternalMailQueue WITH ACTIVATION (STATUS = ON);
       SET @localmessage = FORMATMESSAGE(14639, SUSER_SNAME())
       exec msdb.dbo.sysmail_logmailevent_sp @event_type=1, @description=@localmessage
    END
RETURN @rc
The user get the error, because she does not have any permission on the queue in question. To be able to alter the queue, the following applies according to Books Online:
Permission for altering a queue defaults to the owner of the queue, members of the db_ddladmin or db_owner fixed database roles, and members of the sysadmin fixed server role.
Note that is would be db_ddladmin or db_owner in msdb. Now, supposedly the queue is already active, and in that case I think that it is sufficient that the user has VIEW DEFINITION on the view. This would permit her to see the row in sys.service_queues,
why there would be no need to call sysmail_start_sp.
Altertanively, change the check to:
DECLARE @isenabled bit
SELECT @isenabled = (SELECT is_receive_enabled FROM msdb.sys.service_queues
               WHERE name = N'ExternalMailQueue')
IF @isenabled = 0
   EXEC @rc = msdb.dbo.sysmail_start_sp
The idea here is that, if the user has no permission to read the information in the DMV, @isenabled will be NULL, and you just pray and hope that the queue is up and running.
I suspect that the reason this worked for you on SQL 2005 is that on that instance someone at some point in made all the required configurations for it to work, but all that is forgotten now. That happens to me too.
If you really want the user to be able to start the queue, I have some better ideas than adding her to a role, but I skip the details for now.
Erland Sommarskog, SQL Server MVP, [email protected]