cannot send mail

[kagrahar]

I am new to civiCRM and having difficulties with mailings. I can send individual emails but not event
I am getting the following error messages. All the settings seems to be correct.

Sorry but we are not able to provide this at the moment.
Failed to set sender: b.7.7.7be1d40f4dc5af24@ [SMTP: Invalid response code received from SMTP server while sending email. This is often caused by a misconfiguration in Outbound Email settings. Please verify the settings at Administer CiviCRM >> Global Settings >> Outbound Email (SMTP). (code: 501, response: : domain missing or malformed)]

Strict warning: Non-static method PEAR::raiseError() should not be called statically, assuming $this from incompatible context in Net_SMTP->_parseResponse() (line 375 of /home5/uronlin1/public_html/kcob/sites/all/modules/civicrm/packages/Net/SMTP.php).
   •   Strict warning: Non-static method PEAR::raiseError() should not be called statically, assuming $this from incompatible context in Mail_smtp->send() (line 295 of /home5/uronlin1/public_html/kcob/sites/all/modules/civicrm/packages/Mail/smtp.php).
   •   Warning: mysqli_error() expects parameter 1 to be mysqli, resource given in CRM_Core_Error::handle() (line 224 of /home5/uronlin1/public_html/kcob/sites/all/modules/civicrm/CRM/Core/Error.php).