Newsletter Builder > Custom Sender

Hi,

In General settings i have entered a custom SMTP Sender.
I have test the configuration by doing a password reset, everything is fine no problem.

On another part i have Newsletter Builder Plugin installed.
When i try to send test Message or Message to the final list, nothing happen, email does not send.

Little precision, by using "Php mail() built in function" in General settings, my Newsletter plugin was working fine.

Can somebody help me to solve my problem?