I have gotten quite a few emails asking me on how I sent an automatic email to those who commented on my blog. First off, it is not just an automatic email, but a thank you email. I wanted to make sure that people remembered my site and knew that I constantly updated it. For those who are regulars, I blog almost on a daily basis.
I use the WordPress plugin called Thank Me Later by Brendon Boshell. It is not your normal auto-responder type email as it really does not sign you up for anything. As the blog owner, you can specify in the plugin settings when the email is sent out and how often. For me, usually it is sent 1 hour after a visitor commented on the site and only once. Others might want to send out once a month.
I think it is a great plugin. Unlike the Twitter Auto-DM (Automatic Direct Message) ability, this tool is great to help your blog visitors feel welcomed. The message that is sent can be customized and you can include links to special parts of your site or your RSS feed.
I think there could be potential to turning this plugin to have auto-responder features. However, I am fairly content as this is a good tool to inform visitors at least once about attracting them back to your website.
Have you tried this plugin?