This is the default service which is provided by PaxFlow to send emails from the system. All emails are sent from the email address "no-reply[@]paxflow.io". There is an option to BCC all sent emails in case you would like to receive a copy into your external inbox.
Enter an email for BCC'ing all sent emails if you want:
Advanced Mailing options:
Sendgrid (paid subscription required)
HelpScout (paid subscription required)