Hi @rosbiffer,
RegistrationMagic has two ways using which you can send email to a list of users. You can use the Automation feature, which gives you the flexibility to filter users based on a set of parameters before sending the email. Or you can use the more simpler Bulk Email feature, which will send an email to all the users registered through a form, without any filtration involved.
As for the number of emails that can be sent at once, that depends on your SMTP or email server configuration. Whichever option you have selected from the backend. Most web servers (and personal email SMTPs) set a limit for outgoing emails. We would suggest combining RegistrationMagic email sending system with a professional SMTL service like SendGrid SMTP service for added reliability.
Additionally, RegistrationMagic will show sent emails in its Users and Outbox areas for record purposes.