[wp-trac] [WordPress Trac] #33037: Mail not being send in PHP 5.5.25 and 5.6.9 /PCRE 8.36

[WordPress Trac]

#33037: Mail not being send in PHP 5.5.25 and 5.6.9 /PCRE 8.36
--------------------------+-----------------------------
 Reporter:  jrf           |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Mail          |    Version:  trunk
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 Mail is not being send and a `preg_match(): Compilation failed: internal
 error: previously-checked referenced subpattern not found at offset 728`
 error is logged.

 This is a PHP bug affecting PHP version 5.5.25 and 5.6.9 when run as an
 apache handler (i.e. mod_php) (status for 5.5.26 and 5.6.10 unconfirmed)
 and possibly more versions - including custom compilations - which include
 PCRE Library Version 8.36.

 PHPMailer has not been patched for this bug, though a work-around has been
 published:

 {{{
 class myMailer extends PHPMailer {
     public static function validateAddress($address, $patternselect =
 'php')
     {
         return parent::validateAddress($address, $patternselect);
     }
 }
 }}}

 This work-around forces the PHPMailer class to fall back to using the PHP
 filter extension which *should* be available by default since 5.2.0, but
 may not always be in custom PHP compilations.

 While this is not a WP bug in and of itself, it does have an impact on any
 WP website running on a PHP version using PCRE 8.36.


 References:
 https://github.com/PHPMailer/PHPMailer/issues/429
 https://github.com/PHPMailer/PHPMailer/issues/425
 https://github.com/PHPMailer/PHPMailer/issues/424
 https://github.com/PHPMailer/PHPMailer/issues/439
 http://www.exakat.io/wordpress-not-sending-mail-while-php-5-6-9-does/

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Ticket URL: <https://core.trac.wordpress.org/ticket/33037>
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