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It’s not a standalone plugin requires installed Contact Form 7
This plugin solves problem of e.g. email verification or email confirmation.
Just create second field with <code>_confirm</code> at the end of the field name. Look in the screenshots for example.

cf7 Confirm Field

Plugin allows to make sure that e.g. emails in two fields are the same

Christian Sabo

The Flamingo plugin by Takayuki Miyoshi does save all email addresses entered into CF7 forms. If you don’t want or need that, you can disable this function by activating my plugin.
<h3>Translations</h3>
If you wish to help translate this plugin, you are most welcome! 
To contribute, please visit <a href="https://translate.wordpress.org/projects/wp-plugins/disable-flamingo-addressbook/" rel="nofollow ugc">translate.wordpress.org</a>
Keep in mind that if you’re not PTE or GTE for your language, you have to notify someone to approve your contributed strings. This can be done via <a href="https://wordpress.slack.com/" rel="nofollow ugc">Slack</a> or by writing a request on <a href="https://make.wordpress.org/polyglots/" rel="nofollow ugc">https://make.wordpress.org/polyglots/</a>
To find the translation team for your locale, please visit <a href="https://make.wordpress.org/polyglots/teams/" rel="nofollow ugc">https://make.wordpress.org/polyglots/teams/</a>
<h3>Credits</h3>
Special Thanks go to <a href="https://wordpress.org/support/users/herrschuessler/" rel="ugc">Christoph Schuessler</a>.

Disable Flamingo Addressbook

With this plugin activated, Flamingo will not add any data to its address book.

cf7 Confirm Field vs Disable Flamingo Addressbook