#0 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/MailboxHeader.php(261): Swift_Mime_Headers_MailboxHeader->_assertValidAddress('')
#1 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/MailboxHeader.php(106): Swift_Mime_Headers_MailboxHeader->normalizeMailboxes(Array)
#2 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/MailboxHeader.php(63): Swift_Mime_Headers_MailboxHeader->setNameAddresses(Array)
#3 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/SimpleHeaderFactory.php(58): Swift_Mime_Headers_MailboxHeader->setFieldBodyModel(Array)
#4 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/SimpleHeaderSet.php(68): Swift_Mime_SimpleHeaderFactory->createMailboxHeader('To', Array)
#5 vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/SimpleMessage.php(329): Swift_Mime_SimpleHeaderSet->addMailboxHeader('To', Array)
#6 system/modules/core/library/Contao/Email.php(407): Swift_Mime_SimpleMessage->setTo(Array)
#7 system/modules/warenkorb_anfrage_bestellung/modules/ModuleBestellanfrageSenden.php(140): Contao\Email->sendTo(NULL)
#8 system/modules/core/modules/Module.php(287): ModuleBestellanfrageSenden->compile()
#9 system/modules/core/elements/ContentModule.php(59): Contao\Module->generate()
#10 system/modules/core/library/Contao/Controller.php(484): Contao\ContentModule->generate()
#11 system/modules/core/modules/ModuleArticle.php(213): Contao\Controller::getContentElement(Object(Contao\ContentModel), 'main')
#12 system/modules/core/modules/Module.php(287): Contao\ModuleArticle->compile()
#13 system/modules/core/modules/ModuleArticle.php(67): Contao\Module->generate()
#14 system/modules/core/library/Contao/Controller.php(417): Contao\ModuleArticle->generate(false)
#15 system/modules/core/library/Contao/Controller.php(277): Contao\Controller::getArticle(Object(Contao\ArticleModel), false, false, 'main')
#16 system/modules/core/pages/PageRegular.php(133): Contao\Controller::getFrontendModule('0', 'main')
#17 system/modules/core/controllers/FrontendIndex.php(285): Contao\PageRegular->generate(Object(Contao\PageModel), true)
#18 index.php(20): Contao\FrontendIndex->run()
#19 {main}