As for my problems, they came from the fact that my nickname contains a symbol like that of Alex T AND that the new table bx_notifications_queue did not have the same charset as the sys_queue_email table. So all notifications that contained my nickname were messy to move from one table to another. By setting the delay setting to zero, I did not use the new table and it worked, so for me it's solved. I explain that in case someone has this problem.