wp_mail() bug with UTF-8-named attachment

[Blue Liquid Designs]

Hi,

I came across a problem with phpmailer when attaching UTF-8 encoded files to the email. The file is correctly sent but the attached filename is incorrect.

For instance, Τεστ1_Τεστ2.pdf becomes 1_Τεστ2.pdf.

I tracked it down to line 1984 of /wp-includes/class-phpmailer.php, which is

$filename = basename($path);

From the research I did, unless the correct locale has been set using setlocale() before running basename() problems like this will occur.

The simple solution would be to run setlocale() for the correct language before sending mail, but it's not possible to determine the correct locale if you have users who write in multiple languages using the website.

Since WordPress has been pushing internationalisation hard in the last few updates this seems like another good step forward to support multi-languages.

[johnbillion]

Thanks for the report.

This needs to be reported upstream to PHPMailer: ​https://github.com/PHPMailer/PHPMailer/issues

[desrosj]

Because this is an issue in PHPMailer and requires an issue on their repository, I am going to close this out as reported-upstream.

Worth noting, PHPMailer has received some significant updates since this ticket was opened. The most recent version of PHPMailer was merged into WP Core in [48033] for version 5.5. It's possible that this issue was resolved with that update.