SQL Server 2017

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6 rows affected

-- test setup
declare @stat table(
   run int,
   Email varchar(50));
DECLARE @cnt INT = 0;
-- test loop
WHILE @cnt < 500
BEGIN
   -- the query
   declare @rnd int = ABS(CHECKSUM(NewId()));

with weighted as (
      select Email, param1, param2, count(*) * (1 + param1 + param2) n
      from Benutzer
      group by Email, param1, param2
   ), ranges as (
     select Email, sum(n) over(order by Email)- n + 1 n1, sum(n) over(order by Email) n2, sum(n) over() sn
     from weighted
   ), h as (
     select 1 level, t2.*, ABS(CHECKSUM(NewId())) r, @rnd  % t2.sn + 1  k
	 from ranges t2 
	 where (@rnd  % t2.sn + 1) between t2.n1 and t2.n2

union all

select case when t2.Email = h.Email then level else level + 1 end
	     , t2.*
		 , ABS(CHECKSUM(NewId())),  r % t2.sn + 1
	 from ranges t2 
	 join h on r % t2.sn + 1  between t2.n1 and t2.n2 
	 where level <=1
   )
   insert @stat(Email, run)
   select top(1) with ties Email, @cnt
   from h
   order by row_number() over(partition by level order by newid());
   --
   SET @cnt += 1;
END;

-- test results      
select Email, count(*) n
  , count(*) * 100.0 / sum(count(*)) over() p
--, count(distinct run) runs, 
from @stat
group by Email;

Email	n	p
Test@test.com	68	6.800000000000
Test1@test.com	179	17.900000000000
Test2@test.com	159	15.900000000000
Test3@test.com	246	24.600000000000
Test4@test.com	180	18.000000000000
Test5@test.com	168	16.800000000000