Email and Server performance – problems in sending emails to 400 users?

Hello,

I have some questions about the effects of the plugin.
Do you think I might have issues for sending notifications to the members of a group of 400 users?
Does it have to do with the hosting? Am I allowed to send all these email or I might appear as spammer?

Thank in advance

https://wordpress.org/plugins/buddypress-group-email-subscription/