WP user potential issue?

Hi, I’m considering trying this great-looking plugin, but have a question. I’d like to acquire subscribers and work towards converting them into paying members. I’m looking for an email subscription model that only requires an email and first name. I presume in mailpoet this will generate a wp_user object? If so, when that subscriber then goes to register, wp will see that their email exists and wont be able to register them, without some creative modification to the registration process (which I can do but would be easier to not have to).

Is this correct? And if so, do you have any suggestions for working around this?

Many thanks,

Jamie

https://www.ads-software.com/plugins/wysija-newsletters/