nholdren

SayMore is a email opt-in plugin that adds users to an ExactTarget list using the web collect method once they comment on a post/page in your blog.

SayMore

An opt-in plugin for collecting email addresses of those who comment on your blog.

erellsworth

Just use Contact Form 7’s normal shortcodes like so:
‘[email* your-email]’ 
‘[checkbox sendinblue-opt-in default:1 “Subscribe” ]’ 
‘[hidden sendinblue-list-id “13”]’
That’s all there is to it.

Contact Form 7 SendInBlue Opt-in Checkbox

Not working

It integrates the form with Send In Blue very well. =)

but if we are using the official SendinBlue plugin, they seem to conflict and the officil plugin stops working.

It is a very useful plugin.

WordPress plugin to add a SendinBlue Opt-in checkbox for Contact Form 7

SayMore vs Contact Form 7 SendInBlue Opt-in Checkbox