Title: fatal error validate_email() already declared (WP multisite)
Last modified: August 16, 2017

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# fatal error validate_email() already declared (WP multisite)

 *  Resolved [nicomollet](https://wordpress.org/support/users/nicomollet/)
 * (@nicomollet)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/)
 * Hello
    New version of Mailjet (v4.2.1) crashed my WordPress multisite, which 
   already declared validate_email() in the core. (wp-includes/ms-deprecated.php
   line 170 in WP 4.7.5)
 * Mailjet should rename the function and/or check with function_exists before declaring
   it.
    Or better, use the core function is_email().
 * Thank you.
    Nico
    -  This topic was modified 8 years, 9 months ago by [nicomollet](https://wordpress.org/support/users/nicomollet/).

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Thread Starter [nicomollet](https://wordpress.org/support/users/nicomollet/)
 * (@nicomollet)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/#post-9413514)
 * It seems there are other functions in the plugin declared without function_exists:
 * my_show_extra_comment_fields
    subscribe_comment_author register_extra_fields
 * Prefix them with “mailjet_” and check with function_exists to prevent fatal crashes!
   Thank you
 *  Plugin Author [Mailjet](https://wordpress.org/support/users/mailjet/)
 * (@mailjet)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/#post-9413793)
 * Hey nicomollet,
 * Sorry for this bug. We are working on the fix right now and will release it ASAP.
 * Best regards,
    Mailjet Plugins Team
 *  Plugin Author [Mailjet](https://wordpress.org/support/users/mailjet/)
 * (@mailjet)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/#post-9413882)
 * Hello again, we’ve just updated the plugin, so that the fatal errors should not
   occur anymore.
 * Please let us know if you face further issues.
 * Thanks!
 *  Thread Starter [nicomollet](https://wordpress.org/support/users/nicomollet/)
 * (@nicomollet)
 * [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/#post-9414736)
 * Everything is ok now, thank you!

Viewing 4 replies - 1 through 4 (of 4 total)

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 * 4 replies
 * 2 participants
 * Last reply from: [nicomollet](https://wordpress.org/support/users/nicomollet/)
 * Last activity: [8 years, 9 months ago](https://wordpress.org/support/topic/fatal-error-validate_email-already-declared-wp-multisite/#post-9414736)
 * Status: resolved