Question very very important

Hello to all,

I know that I am not on the good forum, but the forum of GLPI completely died.

I would like to activate the notifications by e-mail on GLPI but when I made send a test message it tells me "Error of sends of test message" yet two weeks ago it worked correctly. I use the mail server of gmail.

My server OCS&GLPI is on ubuntu. 

Would you have an idea where from it could come?