Joomla Contacts problem help

Hi all coders; i have two website designed with joomla. i have problems with contacts module. i use also artfroms joomla but again i can not contact. my smtp settings is [login to view URL] user write information? then click the submit, e-mail is not sending and blank page will be show and nothing write. i can 4-5 email send with artforms, but now again don' send. i want without problems contact forms. contact forms mean; first one simple contact form, name ,surname, e-mail, subject and message. the other forms will be designed special, like in artforms. ## Deliverables contact forms problem firstly fix the contact forms problem. secondly, fix created forms by artforms or others(modules no imparant) the main problem is the user can not send email to company.