enewsletter not working when sending to groups, all sent, no-one receive

enewsletter: I send mail to group. Everything seems went fine (all messages sent). But no users receive messages.

why?

it worked ’till few days ago …

If I send test email it works.

If I send to group none receive emails.

Web server is working, email accounts too.

Tryed to send trought smpt, php and wp … same result … all message sent but no one receive it.