Automatic E-Mail doesn’t work :(

Hey guys,
i don’t know why but when someone orders an event, he doesn’t get an email and when i accept an order, this error is shown:

Fatal error: Uncaught phpmailerException: Invalid address: in /var/www/web27398925/html/fluxahoi-berlin/wp-includes/class-phpmailer.php:946 Stack trace: #0 /var/www/web27398925/html/fluxahoi-berlin/wp-includes/pluggable.php(352): PHPMailer->setFrom(”, ‘FluxAhoi!’) #1 /var/www/web27398925/html/fluxahoi-berlin/wp-content/plugins/events-manager/classes/em-mailer.php(41): wp_mail(‘matt0@gmx.net’, ‘Buchung best\xC3\xA4t…’, ‘Liebe/r Marco, …’, Array) #2 /var/www/web27398925/html/fluxahoi-berlin/wp-content/plugins/events-manager/classes/em-object.php(1224): EM_Mailer->send(‘Buchung best\xC3\xA4t…’, ‘Liebe/r Marco, …’, ‘matt0@gmx.net’) #3 /var/www/web27398925/html/fluxahoi-berlin/wp-content/plugins/events-manager/classes/em-booking.php(1021): EM_Object->email_send(‘Buchung best\xC3\xA4t…’, ‘Liebe/r Marco, …’, ‘matt0@gmx.net’) #4 /var/www/web27398925/html/fluxahoi-berlin/wp-content/plugins/events-manager/classes/em-booking.php(823): EM_Booking->email() #5 /var/www/web27398925/html/fluxahoi-berlin/wp-content/plugins/e in /var/www/web27398925/html/fluxahoi-berlin/wp-includes/class-phpmailer.php on line 946

Please help 🙁