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.