Weird thing about my subscriber's mailing list

Hello,
A month ago I create a small blog where I review (1 post per week) product (books).
I set up an ugly newsletter form just for the sake to have one.
Since then I didn't notice it but I have up to 600 emails subscribers (now).
First, I thought it's probably a bot or something... but I have up to 5 - 9 emails subscribers per day. it's mostly gmail /hotmail/ yahoo mail account.

How to know if it's fake or not?
I didn't try to send anything yet.

Send some affiliate offers (if you have any). See how it converts. Perhaps they are real and actual buyers? My current list grows at the rate of 2 emails a day ..

mzonas said:

Send some affiliate offers (if you have any). See how it converts. Perhaps they are real and actual buyers? My current list grows at the rate of 2 emails a day ..

Click to expand...

I will, but it's hard to believe they're real.

There isn't another way to check if they are real?