email                           prject_name
rafael.nadal@xyz.com              lab1
rafael.nadal@xyz.com              lab2
rafael.nadal@xyz.com              lab3
TEST@TEST.COM                     shift1
TEST@TEST.COM                     shift2

email                     project_name
rafael.nadal@xyz.com     lab1, lab2, lab3
TEST@TEST.COM            shift1, shift2, shift3

select distinct email ,
STUFF((Select ','+project_name
from dbo.[UMG sent 2016] as  T1
where T1.email=T2.email
FOR XML PATH('')),1,1,'') from dbo.[UMG sent 2016] as T2;

SELECT DISTINCT email,
                STUFF((SELECT ',' + project_name
                       FROM   dbo.[UMG sent 2016] AS T1
                       WHERE  T1.email = T2.email
                       FOR XML PATH('')), 1, 1, '')
FROM   dbo.[UMG sent 2016] AS T2;

SELECT email,
       STUFF((SELECT ',' + project_name
              FROM   dbo.[UMG sent 2016] AS T1
              WHERE  T1.email = T2.email
              FOR XML PATH('')), 1, 1, '')
FROM   dbo.[UMG sent 2016] AS T2
GROUP  BY email;

-- Create the working table ...
IF OBJECT_ID('tempdb..#tmp') IS NOT NULL DROP TABLE #tmp

SELECT ROW_NUMBER() OVER( PARTITION BY email ORDER BY prject_name ) rowId, email, CAST( prject_name AS VARCHAR(500 ) ) prject_name
INTO #tmp
FROM dbo.[UMG sent 2016]
GO

-- Index temp table
CREATE UNIQUE CLUSTERED INDEX _cdx ON #tmp ( rowId, email )
GO

SELECT TOP 100 'before' s, *
FROM #tmp
ORDER BY email


-- Loop through appending the projects
DECLARE @n INT = 1

WHILE @@ROWCOUNT != 0
BEGIN

    IF @n > 99 BEGIN RAISERROR( 'Too many loops!', 16, 1 ) BREAK END    -- Loop safety
    SET @n += 1

    UPDATE t
    SET t.prject_name = CONCAT( t.prject_name, ', ', s.prject_name )
    FROM #tmp t
        INNER JOIN #tmp s ON t.email = s.email
    WHERE t.rowId = 1
      AND s.rowId = @n

END
GO

SELECT TOP 100 'after' s, *
FROM #tmp
WHERE rowId = 1
ORDER BY email

create index ixEmail on [UMG sent 2016](email) include (prject_name)