I have uploaded 100 customer emAils (CSV file) and I see them under my customer list. However, I could not send them an email. They dont show up in shopify email. I only see who signed up through the site.
It's probably because the imported customers were not marked as accepting marketing emails (Accepts Marketing column in the CSV file).
Hmm... I'd expect it to work immediately. What value did you put in the Accepts Marketing column? The value should be yes if you want to import customers as subscribed to marketing emails.
What program/app do you use to edit the CSV file?