Is there a way to add local (@localhost) email accounts?

When adding up an email account or sending mail, user@localhost is not recognised as a valid email address. Is there a way to get eM Client to recognise it as a valid address? I would like to send a receive mail from my local mail server (Mercury) for testing purposes.

My current work around is to make resolve to by editing my host file and setting up mercury to recognise addresses. I would rather not have to do this if possible.

it sounds reasonable - I added it to our list of feature requests.

Thanks and great software by the way.