What are some alternatives?
EuropeanMX - Protects your company by blocking spam and virus before they reach your network.
Dyn - Managed DNS, Outsourced DNS & Anycast DNS
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.
FreeDNS - Free DNS hosting, lets you fully manage your own domain. Dynamic DNS and Static DNS services available. You may also create hosts off other domains that we host upon the domain owners consent, we have several domains to choose from!
SpamTitan - SpamTitan is an anti-spam email solution specifically developed to meet the demands of modern business. Delivering a spam detection rate over 99.9%
No-IP - Dynamic DNS and Managed DNS Provider