After a simple update on my form, the sender gets the following message:

our form could not be submitted for the following reason(s):

Warning: [ err 2/line 1798/PHPMailer.php] popen() has been disabled for security reasons
Warning: [ err 2/line 1798/PHPMailer.php] popen() has been disabled for security reasons
Could not execute: /usr/sbin/sendmail -t -i -f jochemsmusicservicesnl@web021.prod.widos.net
Could not execute: /usr/sbin/sendmail -t -i -f jochemsmusicservicesnl@web021.prod.widos.net

I haven't touched the mail settings in any way.
Using V5, build 1999,
Anyone knows the solution?

Thanks, Pieter

Found the solution! Seems I forgot to re-upload the proper 'user.cfg.php' settings' .
cheers, Pieter