Email Validation and other issues

Hi

Even the incorrect emails are getting stored in the members list / DB .
Invalid address: qweqeYou must provide at least one recipient email address. You must provide at least one recipient email address.
Warning: Cannot modify header information - headers already sent by (output started at /home/public_html/wp-content/plugins/e-newsletter/email-newsletter-files/phpmailer/class.phpmailer.php:464) in /home/public_html/wp-includes/pluggable.php on line 876

Is there anything that I am missing?

Thanks

Kalps