Hi @ryan,
k6, currently, works as follows:
There are VUs which will do as many iterations as fast as possible. If you have set iterations to 1000 and VUs to 1000 then (usually unless your iterations are extremely fast) each VU will do 1 iteration and k6 will finish.
I would argue that unless you need the 1000 iteration to be happening at the same time you should probably use smaller number of VUs and reuse them - let’s say 100VUs and each does 10 iterations using a different email.
You can set noVUConnectionReuse in order to make certain connections won’t be reused between VUs.
Here is explanation how not to use data more then once.