Leniy

You can easily send subscription,notification,newsletter,etc by email to your comments users under one post. 
方便给某篇文章的评论用户发送订阅、通知等邮件。
DEMO:<a href="http://blog.leniy.org/mail-to-all.html" title="示例页面" rel="nofollow ugc">Leniy</a> 
<a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=HAENMLDR2UMFJ&lc=US&item_name=Leniy%20Plugins%20Donation&item_number=plugin%2ddonate&currency_code=USD&bn=PP%2dDonationsBF%3abtn_donate_SM%2egif%3aNonHosted" rel="nofollow ugc">Donate link</a>

Mail To All

You can easily send subscription,notification,newsletter,etc by email to your comments users under one post.

John James Jacoby

Matt Mullenweg

Samuel Wood (Otto)

It’s hard to keep up with a private blog because there’s no good way to subscribe to it. Subscription plugins aren’t great because generally you have a finite number of people you want to get to it and asking each one to do a double-opt-in is annoying, and you still wouldn’t have anything for comments.
This hooks into the new comment and new post actions to send an email to the addresses you enter, so it’s easy to follow the entire conversation even if it’s comments on someone else’s blog posts.

Notifly

Send notification emails of all new posts and new comments to everyone on a list. Great for private blogs.

Mail To All vs Notifly