Do you mean Shopify store owners?
If yes.
Here's one of a lot of things that you do.
-Find someone who provides a good service related to Shopify (You can use Fiverr or a service from BHW).
-Create a landing page about this service.
-Double or triple the price.
-Dropship this service (When someone order from you, pay the service provider and keep the profit)
-Clean your list.
-Start sending slowly and increase everyday based on your results.
You can build your own SMTP server to send your emails, this one needs some syslinux skills and some experience on bulk mailing.
Or use a premade solution to send your emails from multiple Gmail accounts.
Good luck,