Importing contacts from mail accounts using OAuth is a long solved problem which doesn’t have a good implementation. I googled and googled for a good library which imports contacts from Yahoo/GMail/Hotmail. Finally, I was forced to create one by myself. Here are the instructions on how to get it up and running for Yahoo Mail in your server in 2 mins.

1. You need a Yahoo API Key to fetch contacts from Yahoo. Proceed to Yahoo Developer Dashboard and create a key.

Application URL in the createKey page is the URL to which you will be redirected to after a successful/failed login attempt.
Application Domain is be your domain name.
Choose “This app requires access to private user data.” in the Access Scope and under the options which appear below that, select “Read” access for “Yahoo! Contacts”.
Store the API Key, Shared Secret and Application ID carefully.

2. Download Yahoo Social SDK for PHP from http://developer.yahoo.com/social/sdk/php/

$this->config->item(‘yahoo_consumerkey’) is your Yahoo API Key.
$this->config->item(‘yahoo_consumersecret’) is your Yahoo Shared Secret.
$this->config->item(‘yahoo_applicationurl’) is your Application URL you provided in Step 1.
$this->config->item(‘yahoo_applicationid’) is your Yahoo Application ID.

3. Add the following code where the user has to select Yahoo Mail


<a href="<?php echo YahooSession::createAuthorizationUrl($this->config->item('yahoo_consumerkey'), $this->config->item('yahoo_consumersecret'), $this->config->item('yahoo_applicationurl').'?data=abc'); ?>">Fetch Yahoo Contacts</a>

You may remove the ?data=abc if you don’t want to pass any data to Yahoo. Anything you pass here can retrieved back at Application URL as GET parameters.

4. Include the required files from the opensocial SDK library and then add the following snippet to the Application URL you provided in Step 1.

if (YahooSession::hasSession($this->config->item('yahoo_consumerkey'), $this->config->item('yahoo_consumersecret'), $this->config->item('yahoo_applicationid')))
{
    $session = YahooSession::requireSession($this->config->item('yahoo_consumerkey'), $this->config->item('yahoo_consumersecret'), $this->config->item('yahoo_applicationid'));
    $user = $session->getSessionedUser();
    $contacts = $user->getContacts(0, 1000);
    foreach ($contacts->contacts->contact as $contact)
    {
        foreach ($contact->fields as $field)
        {
            if ($field->type == "email")
            {
                $emails[] = $field->value;
            }
        }
    }
    //$_GET['data'] will be equal to "abc" at this page.
}
//$emails array has the email addresses of all the contacts.

5. That’s it folks. It is that simple.

Further reading :
1. http://developer.yahoo.com/social/sdk/php/
2. http://developer.yahoo.com/oauth/