[Answer]-Not able to send email to more than 2 email address

You have a typo.

list=[]        
for email in follower:
    list.append(email.email)

At this point list is already a Python list (you should probably rename this variable because this is confusing and not a good practice).

Then you use it as:

EmailMultiAlternatives(..., bcc=[list], ...)

And that is where is a typo. You are passing a list with a list item whereas you should be passing just a list of strings:

EmailMultiAlternatives(..., bcc=list, ...)