'From' address possibly not having the right format

Problem

In EmailWebformHandler::sendMessage() there is a 'from' address which is being constructed from the name and the mail. Currently it has the the "mail_address " format, but is this format valid? Shouldn't it be "Mail Name "? When using the current format I had quite some issues with the 'From' header containing some other things (in this case was the domain name of the testing server). By changing to "Mail Name " the issues were solved.

Proposed solution

This should be pretty straight forward, something like:

$from = $message['from_mail'];
if (!empty($message['from_name'])) {
  $from = $message['from_name'] . ' <'  . $from . '>';
}

But again, not sure if the current format is really not valid.