Allow issues to be created from emails that do not have a subject

We have two current support requests in which customers would like to be able to create issues from emails that have a blank subject. They state that they cannot guarantee that users will always enter a subject in their email, but that they still really want issues to be created for these emails.

Our current CreateIssueHandler rejects emails that do not have a subject.

So this improvement request is that we consider providing a configuration option so that administrators can decide whether they want emails with no subject to be:

• rejected, or
• accepted with some default subject, with maybe the ability to specify what the default subject would be.