Not able to send email from custom module

Question

How to debug following code.

$transport = $this->transportBuilder
                ->setTemplateIdentifier($emailTemplate)
                ->setTemplateOptions(
                    [
                        'area' => 'adminhtml',
                        'store' => $this->storeManager->getStore()->getId()
                    ]
                )
                ->setTemplateVars($variables)
                ->setFrom($emailSender)
                ->addTo($emailRecipient)
                ->setReplyTo($replyTo, $replyToName)
                ->getTransport();

It is getting failed without any error or exception message.

Answer 1

Issue was with class vendor/magento/module-email/Model/Template/SenderResolver.php

public function resolve($sender, $scopeId = null)
    {
        $result = [];

        if (!is_array($sender)) {
            $result['name'] = $this->_scopeConfig->getValue(
                'trans_email/ident_' . $sender . '/name',
                \Magento\Store\Model\ScopeInterface::SCOPE_STORE,
                $scopeId
            );
            $result['email'] = $this->_scopeConfig->getValue(
                'trans_email/ident_' . $sender . '/email',
                \Magento\Store\Model\ScopeInterface::SCOPE_STORE,
                $scopeId
            );
        } else {
            $result = $sender;
        }

        if (!isset($result['name']) || !isset($result['email'])) {
            throw new \Magento\Framework\Exception\MailException(__('Invalid sender data'));
        }

        return $result;
    }

I am passing the string in setFrom which is creating the problem.
Fixed it by passing the array.
Changed

setFrom($emailSender)

to

setFrom(['email'=> $emailSender, 'name'=> $senderName])