SMTP server problem

Hi pippuccio76.
If the code works for sending the first email you could try adding a pause (sleep(5)) between sends in case the SMTP has some restriction.
After sending an email, you are calling $email->clear(true);. This is good practice, but ensure that you are not clearing the email object too soon. You might want to check if the email object is still valid before sending the next email.
Regards.