This plugin creates a page under 'Manage'.  On this page is two lists, one for users who've registered and never commented.

ljmacphee

This plugin creates a page under ‘Manage’. On this page is two lists, one for users who’ve registered and never commented. 
And one for users who’ve commented. The lists show user name, clickable email address, date registered, number of comments and 
the date of the last comment. You can easily email users to find out why they haven’t commented or why they haven’t commented in 
a while.

Alternatives to TTC User Comments

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