actually 0.91 phpmailer is 5.2.8 and the last version with php7 compatibility is 5.2.14.
It would be good to update
Version 5.2.15 is used in GLPi 9.1
Сервис поддержки клиентов работает на платформе UserEcho
Идеи
Version 5.2.15 is used in GLPi 9.1