how to use

First of all, you have to understand that uddeim is not an e-mail solution and works differently from the mail field.

See descripten from the uddeim JED page:

uddeIM allows users of your community to send Private Messages to each other (note that uddeIM is not a webmail component nor an email client). uddeIM wants to be simple and easy-to-use but it offers all the features you need in a Private Messaging System (PMS).uddeIM allows users of your community to send Private Messages to each other (note that uddeIM is not a webmail component nor an email client). uddeIM wants to be simple and easy-to-use but it offers all the features you need in a Private Messaging System (PMS).

If you want to integrate uddeim with Cobalt 7, see this article here.

Can you specify what "use" means ? What do you want to do it ? How should it work ?

no it is good, i have just tested mail field, work fine

thank you