How can I create new type of step in soap ui pro version?

Hi,

Soapui PRO had given so many steps like:
SOAP Test Request
REST Test Request
Data Sink
Groovy Script
etc.

So same way I want o develop my own test step for example:
Email Test Step

First of all, can I extend soap ui to create this type of new step?

If yes than how and what is link of documentation.

Thanks,
Akhilkumar Patel - Test Automation Architecture