Nikolay N.

Simple plugin that will improve your onsite SEO a bit and make all links from the comment section dofollow, if they point to your own domain. Other links that point to external websites will remain nofollow. WP DoFollow Comment Links don’t have any configorations – simply activate it and that’s all.
It also works with WordPress installations that reside in a subfolder. For example, WordPress installed in example.com/blog, separate from the main website example.com.
If you have any questions or suggestion, hit me up… nnikolaev [at] sematigo.co.uk

WP DoFollow Comment Links

The plugin automatically makes all the comment links to your own domain dofollow, while all external links remain nofollow.

English 
140follow removes NOFOLLOW from author link if the comment has more than XXX characters. 
The character count can be adjusted at the admin pannel. NOFOLLOW also can be added 
to single comments if you add “/dontfollow” to the end of the author link.
Deutsch 
Das Plugin ersetzt rel=”external nofollow” durch rel=”external” aus dem Autor-Link, 
wenn der Kommentar mehr als XXX Zeichen besitzt. Die Anzahl der Zeichen kann 
einfach im Adminbereich beliebig eingestellt werden.
Einzelnen Kommentaren kann das NOFOLLOW-tag wieder hinzugefügt werden, wenn 
einfach “/dontfollow” (Danke an Oliver Bockelmann) zum Link hinzugefügt wird.

140follow

140follow removes NOFOLLOW from author link if the comment has more than XXX characters.

WP DoFollow Comment Links vs 140follow