We have a mail service hosted on IN Node.
It uses MailU, along with a relay provided by Selea, which mostly bypasses the restrictions imposed on residential IPs like ours.
The Mail service hosts our official emails, and is also an invite only service for users who are interested in getting a mail account on our service.
Every user gets 2 GB of storage (can be increased on request), and access to the Roundcube webmail.