Php 无法从magento向门店管理员发送电子邮件

即使我选择密件抄送或单独发送电子邮件，我也无法向门店管理员发送电子邮件

我得到的错误是：

exception 'Zend_Mail_Transport_Exception' with message 'Unable to send mail. ' in shopdev/lib/Zend/Mail/Transport/Sendmail.php:137
Stack trace:
#0 /shopdev/lib/Zend/Mail/Transport/Abstract.php(348): Zend_Mail_Transport_Sendmail->_sendMail()
#1 /shopdev/lib/Zend/Mail.php(1194): Zend_Mail_Transport_Abstract->send(Object(Zend_Mail))
#2 /shopdev/app/code/core/Mage/Core/Model/Email/Template.php(454): Zend_Mail->send()
#3 /shopdev/app/code/core/Mage/Core/Model/Email/Template.php(506): Mage_Core_Model_Email_Template->send('', '', Array)
#4 /shopdev/app/code/local/Magestore/Adminneworderemail/Model/Observer.php(39): Mage_Core_Model_Email_Template->sendTransactional('sales_email_ord...', 'sales', '', '', Array)
#5 /shopdev/app/code/local/Magestore/Adminneworderemail/Model/Observer.php(10): Magestore_Adminneworderemail_Model_Observer->sendAdminOrderNotification('158')
#6 /shopdev/app/code/core/Mage/Core/Model/App.php(1338): Magestore_Adminneworderemail_Model_Observer->onepageCheckoutSuccess(Object(Varien_Event_Observer))
#7 /shopdev/app/code/core/Mage/Core/Model/App.php(1317): Mage_Core_Model_App->_callObserverMethod(Object(Magestore_Adminneworderemail_Model_Observer), 'onepageCheckout...', Object(Varien_Event_Observer))
#8 /shopdev/app/Mage.php(448): Mage_Core_Model_App->dispatchEvent('sales_model_ser...', Array)
#9 /shopdev/app/code/core/Mage/Sales/Model/Service/Quote.php(210): Mage::dispatchEvent('sales_model_ser...', Array)
#10 /shopdev/app/code/core/Mage/Sales/Model/Service/Quote.php(249): Mage_Sales_Model_Service_Quote->submitOrder()
#11 /shopdev/app/code/local/TM/FireCheckout/Model/Type/Standard.php(1131): Mage_Sales_Model_Service_Quote->submitAll()
#12 /shopdev/app/code/local/TM/FireCheckout/controllers/IndexController.php(1419): TM_FireCheckout_Model_Type_Standard->saveOrder()
#13 /shopdev/app/code/core/Mage/Core/Controller/Varien/Action.php(418): TM_FireCheckout_IndexController->saveOrderAction()
#14 /shopdev/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('saveOrder')
#15 /shopdev/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#16 /shopdev/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#17 /shopdev/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#18 /shopdev/index.php(99): Mage::run('', 'store')
#19 {main}

在apache中没有错误，但在邮件日志中有：

1Y0WeU-0001hT-SV SMTP connection outbound 1418653774 1Y0WeU-0001hT-SV

我已经找了几天的解决办法，但我想不出来。我想说的是，发送给客户的电子邮件已经发送，并且工作正常