You can send emails to anyone else with an email address ... google, yahoo or whatever
Yahoo is an email site. So... If you know their email you can find them. And if you have a facebook You can connect it and all your friends' emails would be in your contacts.
Yahoo, gmail, and facebook
Yahoo is known where your friends send you emails and you send them emails back.
It is very easy to obtain a Yahoo email account. You simply need to go to Yahoo's homepage and sign up for a new email address. Yahoo's emails are free and accessible from anywhere.
You need to mark the high priority emails in Yahoo. By accessing the priority inbox, you can then choose to send the emails.
With Yahoo! Mail, you can not only send plain text emails or messages containing attachments.
facebook one or yahoo, hotmail
there would be a block button the the upper right corner of the email just click the block button then confirm.
you can block emails from specific senders by clicking block sender in Microsoft Outlook Or mark the sender as Spam in gmail/yahoo. In this case the email from that sender will always go to Trash and will be deleted after 30 days or as per the settings done by you to handle trash emails.
of course they are
One is that make sure you have your friends as close friends or add an app called "are you happy or sad"