Configure a mail server you want to use for mailing in WordPress
Quickly adds Facebook Send & Like buttons to your blog posts.
Send a SMS via WordPress using Airtelco srl services.
This plugin stores tokens from apps used for push notifications. It creates an api endpoint which your app can send tokens to and also supports a key
Send SMS via Bongolive services in wordpress
Send SMS via wordpress
Allow visitors to e-mail themselves the URL of the current page.
XMPP sender allows to send (and receive) notifications about new comments in blog. Also it can override email function to xmpp for your blog.
dont_send_mail does't let wordpress-mu send mail at all.