Notice (8): Undefined index: From when fetching message response from Google API-PHP Client - gmail-api

Question

I am trying to list user messages in GMail Inbox.
$client = $this->getClient();
$service = new \Google_Service_Gmail($client);
$opt_param = array('labelIds' => 'INBOX');
$messagesResponse = $service->users_messages->listUsersMessages($user, $opt_param);
for ($i = 0; $i < $total; $i++) {
$messageToGet = ($messagesResponse->messages[$i]->id);
$message = $service->users_messages->get($user, $messageId);
$names = array_column($message->payload->headers, 'name');
$values = array_column($message->payload->headers, 'value');
$mail = array_combine($names, $values);
$senderMail = explode("<", $mail['From']);
if (count($senderMail) == 1) {
if (strpos($senderMail[0], '#') !== false) {
$senderName = [];
$domain[0] = substr($senderMail[0], strpos($senderMail[0], "#") + 1);
} else {
Log::info('Sender email could not be found');
return;
}
} else {
$senderName = [];
if ($senderMail[0] != "") {
$senderName = $senderMail[0];
$senderName = explode(" ", $senderName);
}
$senderMail = explode(">", $senderMail[1]);
$domain = explode("#", $mail['From']);
$domain = explode(">", $domain[1]);
}
...
}
When I tried to fetch 'From' from this $message response, it is throwing an undefined index error while fetching response for a message.
Notice: Notice (8): Undefined index: From in [File]
When I tried to debug the messages response return by the google api-php client, it resulted as below for all the messages
[16] => Google\Service\Gmail\MessagePartHeader Object
(
[name] => From
[value] => "Firstname Lastname" <firstname.lastname#gmail.com>
[internal_gapi_mappings:protected] => Array
(
)
[modelData:protected] => Array
(
)
[processed:protected] => Array
(
)
)
For one message, it returned
[16] => Google\Service\Gmail\MessagePartHeader Object
(
[name] => FROM
[value] => noreply#<domain>.org
[internal_gapi_mappings:protected] => Array
(
)
[modelData:protected] => Array
(
)
[processed:protected] => Array
(
)
)
Can anyone kindly let me know why the value of [name] key differs from From to FROM? Are there any more formats for the [name] key?
Thanks in Advance.