SMTP server/clientApp in C#

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C#

SMTP

Hi,
I working on my final progrrming project.
I'm creatine in Visual studio 2013 a smtp server and clenit App,that also including chat function.
In my client applictaion i have first login form, and after the user log in, the mailing box(and the inbox and the chat) form opens.

The server side connectns to sql server DB , which including all the information of the mail and the user.
I tried to sent user data from server to cleint with WCF, but I don't understand how to send also the mails with smtp protocaol from cleint to Smtp and back(I must use smtp protocol that I cretae by myself-without using smtp builded classes of microsoft).

Hope you can help me with this