Basic:
Open the default mail program and use the filled-in TOS field to create a new message.

<a href="mailto:someone@yoursite.com">Email Us</a>  

Add a topic

Open the default mail program that created the new message with the TO and SUBJECT fields already filled out. Basically, the parameters we add are affected by the href value.

The space in the theme may work fine, but for super sure, you can replace spaces with “% 20”.

<a href="mailto:someone@yoursite.com?subject=Mail from Our Site">Email Us</a>  

Add CC and BCC

Open the default mailer, and use the TO, SUBJECT, CC, and BCC fields to create a new message that is already filled out. Basically, we add the parameters cc and bcc to the href value.

Also note that you can add multiple values to CC and BCC, separated by commas.

<a href="mailto:someone@yoursite.com?cc=someoneelse@theirsite.com, another@thatsite.com, me@mysite.com&bcc=lastperson@theirsite.com&subject=Big%20News">Email Us</a>

Add the body text

Just add the body parameter to the list of parameters we are using to grow.

<a href="mailto:someone@yoursite.com?cc=someoneelse@theirsite.com,
 another@thatsite.com, me@mysite.com&bcc=lastperson@theirsite.com&subject=Big%20News&body=Body-goes-here">Email Us</a>