inspart on "[Plugin: Contact Form 7] CF7 + WP-Mail-SMTP - does not send e-mails"

Hi,
I have installed the plug CF7 and WP-Mail-SMTP because CF7 did not send emails. With WordPress control panel I can send test emails but on-line from the page I can't anymore, I have a message in a red box that the message has not been sent. All data smtp, port, etc are well-written, and the client is upset :( Any ideas
please help,
Ola

http://wordpress.org/plugins/contact-form-7/