A custom Preference that opens a new email in the user's default email app.

EmailPreference.java

package com.faizvisram.android.preference;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.preference.Preference;
import android.util.AttributeSet;

/**
 * Created by Faiz Visram.
 * 
 * A custom Preference that opens a new email in the user's default email app.
 * 
 * @param to        Comma-separated list of email addresses for 'to' field in the email.
 * @param cc        Comma-separated list of email addresses for 'cc' field in the email.
 * @param bcc       Comma-separated list of email addresses for 'bcc' field in the email.
 * @param subject   Subject line of the email.
 * @param body      Body of the email.
 * 
 */
public class EmailPreference extends Preference implements Preference.OnPreferenceClickListener {

    private String mToAddress;
    private String mCcAddress;
    private String mBccAddress;
    private String mSubject;
    private String mBody;

    /**
     * Perform inflation from XML and apply a class-specific base style. This
     * constructor of Preference allows subclasses to use their own base
     * style when they are inflating. For example, a {@link CheckBoxPreference}
     * constructor calls this version of the super class constructor and
     * supplies {@code android.R.attr.checkBoxPreferenceStyle} for <var>defStyle</var>.
     * This allows the theme's checkbox preference style to modify all of the base
     * preference attributes as well as the {@link CheckBoxPreference} class's
     * attributes.
     *
     * @param context  The Context this is associated with, through which it can
     *                 access the current theme, resources, {@link SharedPreferences},
     *                 etc.
     * @param attrs    The attributes of the XML tag that is inflating the preference.
     * @param defStyle The default style to apply to this preference. If 0, no style
     *                 will be applied (beyond what is included in the theme). This
     *                 may either be an attribute resource, whose value will be
     *                 retrieved from the current theme, or an explicit style
     *                 resource.
     * @see #Preference(android.content.Context, android.util.AttributeSet)
     */
    public EmailPreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs);
    }

    /**
     * Constructor that is called when inflating a Preference from XML. This is
     * called when a Preference is being constructed from an XML file, supplying
     * attributes that were specified in the XML file. This version uses a
     * default style of 0, so the only attribute values applied are those in the
     * Context's Theme and the given AttributeSet.
     *
     * @param context The Context this is associated with, through which it can
     *                access the current theme, resources, {@link SharedPreferences},
     *                etc.
     * @param attrs   The attributes of the XML tag that is inflating the
     *                preference.
     * @see #Preference(android.content.Context, android.util.AttributeSet, int)
     */
    public EmailPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs);
    }

    /**
     * Constructor to create a Preference.
     *
     * @param context The Context in which to store Preference values.
     */
    public EmailPreference(Context context) {
        super(context);
        init(context, null);
    }

    private void init(Context context, AttributeSet attrs) {
        setOnPreferenceClickListener(this);

        if (attrs != null) {
            mToAddress = attrs.getAttributeValue(null, "to");
            mCcAddress = attrs.getAttributeValue(null, "cc");
            mBccAddress = attrs.getAttributeValue(null, "bcc");
            mSubject = attrs.getAttributeValue(null, "subject");
            mBody = attrs.getAttributeValue(null, "body");
        }
    }

    /**
     * Called when a Preference has been clicked.
     *
     * @param preference The Preference that was clicked.
     * @return True if the click was handled.
     */
    @Override
    public boolean onPreferenceClick(Preference preference) {
        Intent intent = new Intent(Intent.ACTION_SENDTO);
        String uri = "mailto:";

        if(mToAddress != null) {
            uri += Uri.encode(mToAddress);
        }
        uri += "?";

        if (mCcAddress != null) {
            uri += "cc=" + Uri.encode(mCcAddress) + "&";
        }
        if (mBccAddress != null) {
            uri += "bcc=" + Uri.encode(mBccAddress) + "&";
        }
        if (mSubject != null) {
            uri += "subject=" + Uri.encode(mSubject) + "&";
        }
        if (mBody != null) {
            uri += "body=" + Uri.encode(mBody);
        }

        intent.setData(Uri.parse(uri));
        getContext().startActivity(Intent.createChooser(intent, "Send from..."));

        return true;
    }
}

pref_general.xml

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">

    <com.faizvisram.android.preference.EmailPreference
        android:title="Example EmailPreference"
        to="example1@mail.com,example2@mail.com"
        cc="cc.me@mail.com"
        bcc="bcc.me@mail.com"
        subject="Example Subject"
        body="Example body.\n\nLook at me, I'm an email!" />

</PreferenceScreen>