a) Can I access my mail through an IP address?

No. You must always use a URL address. PTR records are not supported.
b) How many email addresses can I create?

There is no fixed limit on the number of email addresses that can be created.
c) Can I send mass messages using my email address?

Absolutely, no! There are SMTP quota restrictions, but you can experiment with them by visiting the Smatermail mass messaging documentation.
d) How do I change my MX records

You can change these records in the panel. For any questions, please contact us online or by phone.